The catalytic activity of copper-manganese (CuMn2) mixed oxide nanoparticles (Cu/Mn=1:2) has been studied for the selective oxidation of benzylic alcohols to the corresponding aldehydes using molecular oxygen as an oxidizing agent. The CuMn2 mixed oxide showed excellent catalytic activity for the oxidation of benzylic alcohols to the corresponding aldehydes with high selectivity (>99%). The complete conversion (100%) of all the benzylic alcohols to the corresponding aldehydes is achieved within a short reaction period at 102°C. The catalytic performance is obtained to be dependent on the electronic and steric effects of the substituents present on the phenyl ring. Electron withdrawing and bulky groups attached to the phenyl ring required longer reaction time for a complete conversion of the benzylic alcohols.