Cycloalkanes are transformed into the corresponding cycloalkenes by treatment with tert-butyl hydroperoxide (TBHP) in pyridine/acetic acid solution in the presence of Cu(OAC)2.H2O. When iron salts are used instead of copper salts, the major reaction product is the corresponding ketone. Differences between the iron-catalyzed and the copper-catalyzed reactions support a metal-dependent reaction pathway.