Catalytic amounts of RuCl2(PPh3)3 in the presence of excess of N-methylmorpholine N-oxide (NMO) in DMF, oxidizes secondary alcohols to ketones. Spectral and electrochemical studies reveal the formation of an oxocomplex of Ru(IV), on adding excess of NMO. In the proposed mechanism, the Ru(IV)-oxo complex formed from Ru(II) and NMO, attacks the substrate in the rate determining step. © 1986 Indian Academy of Sciences.