Ruthenium(II) perchlorate complexes, [Ru(dppm)(3)(ClO4)]ClO4, 1, Ru(dppe)(3)(ClO4)]ClO4, 2, [Ru(dpae)(3)(ClO4)]ClO4, 3, catalyse the oxidation of cyclohexene in the presence of cumene hydroperoxide (CHP) under homogeneous liquid phase. The products of oxidation are 2-cyclohexen-1-ol and 2-cyclohexenone. Linear alkenes like 1-heptene and 1-octene are not efficiently oxidised under these conditions. Solvent influences the rate of oxidation considerably. N-methylmorpholine-N-oxide (NMO) and CHP are compared for their oxidising ability. (C) 1997 Elsevier Science B.V.