Six dioxomolybdenum(VI) complexes of Schiff-bases derivatives of trans-1,2-diaminocyclohexane and R-salicylaldehyde as well as 2-hydroxynaphthaldehyde have been synthesised and characterized by IR, UV-Vis and NMR-spectroscopic methods. The catalytic activities of the complexes in the reaction of epoxidation of cyclohexene and 1-octene with tert-butyl hydroperoxide (TBHP) as oxidant have been studied. (C) 2003 Elsevier B.V. All rights reserved.