Indirect electrochem. oxidn. of o-nitrotoluene to o-nitrobenzaldehyde by Co(III) was studied. The highest aldehyde yield (.apprx.80%) is obtained in dispersing a 70-fold excess of o-nitrotoluene in a soln. of Co2(SO4)3 in 60% H2SO4 at 12 Deg. The influence of acid concn. excess of nitrotoluene and presence of a catalyst are discussed and found to be compatible with a mechanism proposed by C. E. Bawn (1951). [on SciFinder (R)]