The radiation-induced oxidation of bis/1,2-dicarbollyl/cobalt/III/ acid by OH radicals in deaerated/aerated aqueous solutions has been investigated. 8-Monohydroxy-, and 8,8-dihydroxy-derivatives have been identified as products of the -radiolysis. For the different conditions the following radiationchemical yields were observed: in the presence of N2 atmosphere G/OHDCC/=1.58, in aerated solution 2.11 and 3.04 in a solution saturated with CCl3.