CORPORATE OFFICE PROPERTIES TRUST SCHEDULE III - REAL ESTATE DEPRECIATION AND AMORTIZATION DECEMBER 31, 2001 (DOLLARS IN THOUSANDS)

INITIAL COST -------------------------------- BUILDING AND LAND PROPERTY LOCATION BUILDING TYPE ENCUMBRANCES LAND IMPROVEMENTS - ------------------------------- ----------------------- -------------------- ------------------- ------------- ----------------- 751, 753 760, 785 Jolly Road Blue Bell, PA Office 56,047 22,872 88,387 15000 Conference Center Drive Chantilly, VA Office 25,000 9,451 49,517 2730 Hercules Road Annapolis Junction, MD Office 25,593 7,897 31,589 695 Route 46 Fairfield, NJ Office 9,070 3,732 14,927 431 Ridge Road Dayton, NJ Office 11,982 2,782 11,128 7200 Riverwood Drive Columbia, MD Office 8,605 4,085 16,342 6009 - 6011 Oxon Hill Road Oxon Hill, MD Office 9,302 3,432 13,728 6731 Columbia Gtwy Drive Columbia, MD Office 10,396 3,948 14,286 9690 Deereco Road Timonium, MD Office 8,186 3,426 13,705 6950 Columbia Gateway Drive Columbia, MD Office 11,570 3,593 14,258 2721 Technology Drive Annapolis Junction, MD Office 13,740 2,947 14,615 132 National Business Parkway Annapolis Junction, MD Office 12,004 2,917 12,426 429 Ridge Road Dayton, NJ Office 12,617 2,930 11,719 1306 Concourse Drive Linthicum, MD Office 10,181 2,794 11,177 6940 Columbia Gateway Drive Columbia, MD Office 9,476 3,544 9,912 6750 Alexander Bell Drive Columbia, MD Office 9,084 1,263 12,287 375 W. Padonia Road Timonium, MD Office 5,628 2,600 10,401 133 National Business Parkway Annapolis Junction, MD Office 8,151 2,515 10,060 1304 Concourse Drive Linthicum, MD Office 6,980 1,999 10,393 135 National Business Parkway Annapolis Junction, MD Office 7,923 2,482 9,742 141 National Business Parkway Annapolis Junction, MD Office 7,764 2,396 9,583 710 Route 46 Fairfield, NJ Office 5,864 2,152 8,610 870 - 880 Elkridge Landing Road Linthicum, MD Office 8,613 2,298 9,191 1615 and 1629 Thames Street Baltimore, MD Office 5,767 2,079 8,316 134 National Business Parkway Annapolis Junction, MD Office 7,896 3,684 7,528 920 Elkridge Landing Road Linthicum, MD Office 8,230 2,200 8,778 1302 Concourse Drive Linthicum, MD Office 7,567 2,077 8,307 2605 Interstate Drive Harrisburg, PA Office 4,419 2,089 8,355 900 Elkridge Landing Road Linthicum, MD Office 7,289 1,992 7,967 131 National Business Parkway Annapolis Junction, MD Office 6,172 1,904 7,617 2601 Market Place Harrisburg, PA Office 4,079 1,928 7,713 68 Culver Road Dayton, NJ Office 8,315 861 8,793 999 Corporate Boulevard Linthicum, MD Office 7,862 1,187 8,333 7067 Columbia Gateway Drive Columbia, MD Office 6,054 1,829 7,364 6700 Alexander Bell Drive Columbia, MD Office 5,748 1,755 7,019 7467 Ridge Road Hanover, MD Office 5,982 1,628 6,511 1199 Winterson Road Linthicum, MD Office 5,848 1,598 6,392 6740 Alexander Bell Drive Columbia, MD Office 4,769 1,423 5,691 14502 Greenview Drive Laurel, MD Office 4,780 1,481 5,894 7240 Parkway Drive Hanover, MD Office 3,721 1,495 5,980 849 International Drive Linthicum, MD Office 4,959 1,355 5,422 14504 Greenview Drive Laurel, MD Office 4,628 1,428 5,712 1099 Winterson Road Linthicum, MD Office 4,840 1,322 5,290 1190 Winterson Road Linthicum, MD Office 4,884 1,334 5,337 6716 Alexander Bell Drive Columbia, MD Office 4,161 1,241 4,965 9140 Route 108 Columbia, MD Office 6,500 1,637 5,520 911 Elkridge Landing Road Linthicum, MD Office 4,445 1,215 4,858 6345 Flank Drive Harrisburg, PA Office 4,431 1,323 5,264 104 Interchange Plaza Cranbury, NJ Office 4,610 1,327 5,309 8815 Centre Park Drive Columbia, MD Office 4,053 1,251 5,003 1201 Winterson Road Linthicum, MD Office 4,713 1,288 5,151 2711 Technology Drive Annapolis Junction, MD Office (4) 3,055 3,362 4301 Route 1 Monmouth Junction, NJ Office 3,674 1,210 4,839 6340 Flank Drive Harrisburg, PA Office 4,266 1,273 5,067 101 Interchange Plaza Cranbury, NJ Office 4,043 1,158 4,661 891 Elkridge Landing Road Linthicum, MD Office 4,488 1,233 4,926 2701 Technology Drive Annapolis Junction, MD Office (4) 3,084 3,070 938 Elkridge Landing Road Linthicum, MD Office 4,476 1,195 4,775 901 Elkridge Landing Road Linthicum, MD Office 4,169 1,148 4,574

COSTS CAPITALIZED GROSS AMOUNTS SUBSEQUENT TO CARRIED AT CLOSE ACCUMULATED YEAR BUILT DEPRECIATION PROPERTY ACQUISITION OF PERIOD DEPRECIATION OR RENOVATED DATE ACQUIRED LIFE - ------------------------------------ ------------------ ------------------- ------------ ------------- ------------- -------------- 751, 753 760, 785 Jolly Road 99 111,358 (9,321) 1966/1996 10/14/1997 40 Years 15000 Conference Center Drive - 58,968 (111) 1989 11/30/2001 40 Years 2730 Hercules Road 1 39,487 (2,566) 1990 9/28/1998 40 Years 695 Route 46 3,234 21,893 (1,969) 1990 5/28/1998 40 Years 431 Ridge Road 6,936 20,846 (1,893) 1958/1998 10/14/1997 40 Years 7200 Riverwood Drive 35 20,462 (1,308) 1986 10/13/1998 40 Years 6009 - 6011 Oxon Hill Road 1,094 18,254 (1,487) 1990 9/28/1998 40 Years 6731 Columbia Gtwy Drive - 18,234 - (1) 3/29/2000 N/A 9690 Deereco Road 901 18,032 (850) 1988 12/21/1999 40 Years 6950 Columbia Gateway Drive 29 17,880 (1,133) 1998 10/21/1998 40 Years 2721 Technology Drive 1 17,563 (397) 2000 10/21/1999 40 Years 132 National Business Parkway 19 15,362 (514) 2000 5/28/1999 40 Years 429 Ridge Road 356 15,005 (1,283) 1966/1996 10/14/1997 40 Years 1306 Concourse Drive 402 14,373 (643) 1990 11/18/1999 40 Years 6940 Columbia Gateway Drive 107 13,563 (570) 1999 11/13/1998 40 Years 6750 Alexander Bell Drive 5 13,555 (289) 2000 12/31/1998 40 Years 375 W. Padonia Road 48 13,049 (521) 1986 12/21/1999 40 Years 133 National Business Parkway 234 12,809 (941) 1997 9/28/1998 40 Years 1304 Concourse Drive - 12,392 - (1) 11/18/1999 N/A 135 National Business Parkway 66 12,290 (760) 1998 12/30/1998 40 Years 141 National Business Parkway 236 12,215 (830) 1990 9/28/1998 40 Years 710 Route 46 1,021 11,783 (904) 1985 5/28/1998 40 Years 870 - 880 Elkridge Landing Road 42 11,531 (96) 1981 8/3/2001 40 Years 1615 and 1629 Thames Street 1,041 11,436 (850) 1989 9/28/1998 40 Years 134 National Business Parkway 11 11,223 (490) 1999 11/13/1998 40 Years 920 Elkridge Landing Road 74 11,052 (109) 1982 7/2/2001 40 Years 1302 Concourse Drive 471 10,855 (572) 1996 11/18/1999 40 Years 2605 Interstate Drive 222 10,666 (939) 1990 10/14/1997 40 Years 900 Elkridge Landing Road 402 10,361 (844) 1982 4/30/1998 40 Years 131 National Business Parkway 525 10,046 (756) 1990 9/28/1998 40 Years 2601 Market Place 282 9,923 (845) 1989 10/14/1997 40 Years 68 Culver Road 4 9,658 (289) 2000 7/9/1999 40 Years 999 Corporate Boulevard 4 9,524 (325) 2000 8/1/1999 40 Years 7067 Columbia Gateway Drive - 9,193 (61) 2001 8/30/2001 40 Years 6700 Alexander Bell Drive 211 8,985 (114) 1988 5/14/2001 40 Years 7467 Ridge Road 384 8,523 (600) 1990 4/28/1999 40 Years 1199 Winterson Road 154 8,144 (601) 1988 4/30/1998 40 Years 6740 Alexander Bell Drive 830 7,944 (646) 1992 12/31/1998 40 Years 14502 Greenview Drive 465 7,840 (624) 1988 9/28/1998 40 Years 7240 Parkway Drive 345 7,820 (271) 1985 4/18/2000 40 Years 849 International Drive 668 7,445 (496) 1988 2/23/1999 40 Years 14504 Greenview Drive 264 7,404 (550) 1985 9/28/1998 40 Years 1099 Winterson Road 712 7,324 (615) 1988 4/30/1998 40 Years 1190 Winterson Road 642 7,313 (573) 1987 4/30/1998 40 Years 6716 Alexander Bell Drive 988 7,194 (554) 1990 12/31/1998 40 Years 9140 Route 108 34 7,191 (139) 1974/1985 12/14/2000 40 Years 911 Elkridge Landing Road 817 6,890 (628) 1985 4/30/98 40 Years 6345 Flank Drive 134 6,721 (330) 1989 12/3/1999 40 Years 104 Interchange Plaza 41 6,677 (423) 1990 10/30/1998 40 Years 8815 Centre Park Drive 252 6,506 (506) 1987 9/28/1998 40 Years 1201 Winterson Road 21 6,460 (475) 1985 4/30/1998 40 Years 2711 Technology Drive - 6,417 - (1) 11/13/2000 N/A 4301 Route 1 363 6,412 (516) 1986 6/24/1999 40 Years 6340 Flank Drive 50 6,390 (266) 1988 12/3/1999 40 Years 101 Interchange Plaza 533 6,352 (498) 1985 10/30/1998 40 Years 891 Elkridge Landing Road 90 6,249 (62) 1984 7/2/2001 40 Years 2701 Technology Drive - 6,154 (83) 2001 5/26/2000 40 Years 938 Elkridge Landing Road 31 6,001 (60) 1984 7/2/2001 40 Years 901 Elkridge Landing Road 252 5,974 (65) 1984 7/2/2001 40 Years

INITIAL COST -------------------------------- BUILDING AND LAND PROPERTY LOCATION BUILDING TYPE ENCUMBRANCES LAND IMPROVEMENTS - ------------------------------- ----------------------- -------------------- ------------------- ------------- ----------------- 6711 Columbia Gateway Drive Columbia, MD Office - 3,970 1,729 5035 Ritter Road Harrisburg, PA Office 3,736 1,115 4,438 6400 Flank Drive Harrisburg, PA Office 3,659 1,092 4,347 881 Elkridge Landing Road Linthicum, MD Office 3,783 1,034 4,135 7065 Columbia Gateway Drive Columbia, MD Office 3,561 1,081 4,326 939 Elkridge Landing Road Linthicum, MD Office 3,434 938 3,754 921 Elkridge Landing Road Linthicum, MD Office 3,818 1,043 4,174 900 International Drive Linthicum, MD Office 3,705 1,013 4,051 7063 Columbia Gateway Drive Columbia, MD Office 3,411 1,036 4,144 930 International Drive Linthicum, MD Office 3,586 980 3,920 7321 Parkway Drive Hanover, MD Office 3,452 939 3,757 7318 Parkway Drive Hanover, MD Office 3,569 971 3,885 940 Elkridge Landing Road Linthicum, MD Office 3,681 986 3,924 6360 Flank Drive Harrisburg, PA Office 3,049 910 3,622 6760 Alexander Bell Drive Columbia, MD Office 2,982 889 3,558 1340 Ashton Road Hanover, MD Office 3,323 904 3,617 6708 Alexander Bell Drive Columbia, MD Office 2,938 897 3,588 7061 Columbia Gateway Drive Columbia, MD Office 2,725 827 3,310 6385 Flank Drive Harrisburg, PA Office 1,715 811 3,242 800 International Drive Linthicum, MD Office 2,834 774 3,097 1334 Ashton Road Hanover, MD Office 2,704 736 2,943 47 Commerce Cranbury, NJ Office 2,624 756 3,022 437 Ridge Road Dayton, NJ Office 3,086 717 2,866 6724 Alexander Bell Drive Columbia, MD Office 2,313 449 3,082 6405 Flank Drive Harrisburg, PA Office 2,195 655 2,608 5070 Ritter Road- Bldg A Harrisburg, PA Office 1,952 583 2,318 6380 Flank Drive Harrisburg, PA Office 1,973 589 2,344 1331 Ashton Road Hanover, MD Office 2,154 586 2,345 5070 Ritter Road- Bldg B Harrisburg, PA Office 1,708 510 2,028 7 Centre Drive Cranbury, NJ Office 1,631 470 1,879 2 Centre Drive Cranbury, NJ Office 1,667 480 1,919 114 National Business Parkway Annapolis Junction, MD Retail - 364 2,030 95 Shannon Road Harrisburg, PA Office 1,000 472 1,891 75 Shannon Road Harrisburg, PA Office 951 450 1,799 8 Centre Drive Cranbury, NJ Office 1,348 388 1,552 1350 Dorsey Road Hanover, MD Office 1,444 393 1,571 1344 Ashton Road Hanover, MD Office 1,304 355 1,420 6375 Flank Drive Harrisburg, PA Office 715 191 1,499 1341 Ashton Road Hanover, MD Office 1,123 306 1,222 85 Shannon Road Harrisburg, PA Office 586 277 1,109 102 Interchange Cranbury, NJ Office - 641 467 1343 Ashton Road Hanover, MD Office 710 193 773 Commerce 2 Building Harrisburg, PA Office - - 768 1337 Ashton Road Hanover, MD Office - 400 283 Airport Square XXII Linthicum, MD Office - 630 7 6013&6007 Oxon Hill Road Laurel, MD Office - 457 12 1338 Ashton Road Hanover, MD Office 37 50 - 220 National Business Parkway Annapolis Junction, MD Office - - 23 ---------- ---------- --------- $571,800 $191,650 $746,043 ========== ========== =========

COSTS CAPITALIZED GROSS AMOUNTS SUBSEQUENT TO CARRIED AT CLOSE ACCUMULATED YEAR BUILT DEPRECIATION PROPERTY ACQUISITION OF PERIOD DEPRECIATION OR RENOVATED DATE ACQUIRED LIFE - ------------------------------------ ------------------ ------------------- ------------ ------------- ------------- -------------- 6711 Columbia Gateway Drive - 5,699 - (1) 9/28/2000 N/A 5035 Ritter Road 16 5,569 (233) 1988 12/3/1999 40 Years 6400 Flank Drive 25 5,464 (228) 1992 12/3/1999 40 Years 881 Elkridge Landing Road 249 5,418 (394) 1986 4/30/1998 40 Years 7065 Columbia Gateway Drive - 5,407 (36) 2000 8/30/2001 40 Years 939 Elkridge Landing Road 623 5,315 (405) 1983 4/30/1998 40 Years 921 Elkridge Landing Road 60 5,277 (385) 1983 4/30/1998 40 Years 900 International Drive 185 5,249 (382) 1986 4/30/1998 40 Years 7063 Columbia Gateway Drive - 5,180 (34) 2000 8/30/2001 40 Years 930 International Drive 211 5,111 (366) 1986 4/30/1998 40 Years 7321 Parkway Drive 355 5,051 (335) 1984 4/16/1999 40 Years 7318 Parkway Drive 91 4,947 (273) 1984 4/16/1999 40 Years 940 Elkridge Landing Road 29 4,939 (49) 1984 7/2/2001 40 Years 6360 Flank Drive 199 4,731 (223) 1988 12/3/1999 40 Years 6760 Alexander Bell Drive 228 4,675 (277) 1991 12/31/1998 40 Years 1340 Ashton Road 1 4,522 (241) 1989 4/28/1999 40 Years 6708 Alexander Bell Drive 2 4,487 (52) 1988 5/14/2001 40 Years 7061 Columbia Gateway Drive - 4,137 (28) 2000 8/30/2001 40 Years 6385 Flank Drive 10 4,063 (347) 1995 10/14/1997 40 Years 800 International Drive 74 3,945 (302) 1988 4/30/1998 40 Years 1334 Ashton Road 101 3,780 (228) 1989 4/28/1999 40 Years 47 Commerce 1 3,779 (239) 1992/1998 10/30/1998 40 Years 437 Ridge Road 28 3,611 (307) 1962/1996 10/14/1997 40 Years 6724 Alexander Bell Drive - 3,531 - (1) 5/14/2001 N/A 6405 Flank Drive 6 3,269 (136) 1991 12/3/1999 40 Years 5070 Ritter Road- Bldg A 211 3,112 (187) 1989 12/3/1999 40 Years 6380 Flank Drive 58 2,991 (127) 1991 12/3/1999 40 Years 1331 Ashton Road - 2,931 (156) 1989 4/28/1999 40 Years 5070 Ritter Road- Bldg B 43 2,581 (115) 1989 12/3/1999 40 Years 7 Centre Drive 87 2,436 (200) 1989 10/30/1998 40 Years 2 Centre Drive - 2,399 (151) 1989 10/30/1998 40 Years 114 National Business Parkway - 2,394 - (1) 6/30/2000 N/A 95 Shannon Road 3 2,366 (114) 1995 8/12/1999 40 Years 75 Shannon Road 107 2,356 (124) 1995 8/12/1999 40 Years 8 Centre Drive 256 2,196 (229) 1986 10/30/1998 40 Years 1350 Dorsey Road 200 2,164 (123) 1989 4/28/1999 40 Years 1344 Ashton Road 90 1,865 (98) 1989 4/28/1999 40 Years 6375 Flank Drive 37 1,727 (41) 2000 11/4/1999 40 Years 1341 Ashton Road 79 1,607 (107) 1989 4/28/1999 40 Years 85 Shannon Road 3 1,389 (67) 1995 8/12/1999 40 Years 102 Interchange - 1,108 - (1) (3) N/A 1343 Ashton Road 1 967 (52) 1989 4/28/1999 40 Years Commerce 2 Building - 768 - (1) (3) N/A 1337 Ashton Road - 683 - (2) 4/28/1999 N/A Airport Square XXII - 637 - (2) 12/19/2001 N/A 6013&6007 Oxon Hill Road - 469 - (2) 7/30/2001 N/A 1338 Ashton Road 12 62 - (2) 4/28/1999 N/A 220 National Business Parkway - 23 - (1) (3) N/A --------- ---------- ----------- $29,863 $967,558 $(51,552) ========= ========== ===========

(1) Under construction or development at December 31, 2001. (2) Held for future development at December 31, 2001. (3) Development in progress in anticipation of acquisition (4) Encumbrances for property resides in joint venture. The following table summarizes our changes in cost of properties (in thousands): Balance at December 31, 2000 $ 781,242 Property acquisitions 144,780 Building and land improvements 49,809 Sales (8,273) --------------- Balance at December 31, 2001 $ 967,558 =============== The following table summarizes our changes in accumulated depreciation (in thousands): Balance at December 31, 2000 $ 33,271 Depreciation expense 18,697 Sales (416) --------------- Balance at December 31, 2001 $ 51,552 ===============