Preparation of [2’

6’- 3H] nitrofen and [2’

6’- 3H] chloronitrofen were described. [3

5- 3H] chlorobenzene （Ⅱ） was prepared by catalytic halogen- tritium exchange reaction from m- bromo- chlorobenzene （Ⅰ）. Then （Ⅱ） was nitrated with a mixtrue of HNO3 and H2SO4 to give [3

5- 3H] P- chloronitrobenzene （Ⅲ）. Finally （Ⅲ） was condensed with 2

4- dichlorophenol or 2

4

6- trichlorophenol to form [2’

6’- 3H] nitrofen（Ⅳ） and [2’

6’- 3H] chloronitrofen （Ⅴ）. The specific activity of tritiated nitrofen and chloronitrofen was 1.16 and 1.89 TBq/mol respectively

both radiochemical purities were over 95%.