In neutron-irradiated [CpFe(CO)2]2 radioactive FeCp2 and Fe(CO)5 are formed, in addition to the radioactive parent compound. The radiochemical yields before annealing are 1.4, 3.2, and 16.0%, respectively. The predominance of Fe(CO)5 over FeCp2 is in keeping with previous observations. The yield of radioferrocene is not affected by subsequent thermal treatment at up to 75°, while the yields of the two carbonyl-containing compounds are increased up to 5.4 and 20.1%. The ferrocene yield is insensitive to irradiation time and temperature. From this insensitivity it is concluded that the Fe—Cp bonds are reformed by epithermal processes. Similarly the Fe—CO bonds are reformed by thermal as well as epithermal reactions.