Thetrans-dioxo ruthenium (VI) complex, [P(C6H5)3C6H5CH2]+[Ru(O)2OAcCl2] or tetrapropylammonium perruthenate catalyzes the oxidation of secondary alcohols to ketones byN-methylmorpholine-N-oxide (NMO). Kinetic studies showed the formation of a complex between catalyst and substrate (alcohol) as the first step in the mechanism.