Epoxidation of natural terpene (+)-carvone by the system consisting of a catalyst, oxalic acid (co-catalyst) and H2O2 (70% aqueous solution; oxidant) was studied and factorial design methods were applied for the optimization of this reaction. A dinuclear manganese(IV) complex [LMn(O)(3)MnL](PF6)=(L=1,4,7-trimethyl-1,4,7-triazacyclononane) was used as a catalyst, and acetonitrile was employed as a solvent. An analysis by methods of the complete 2(4) factorial design showed that an increase in the catalyst concentration gives a strong positive effect on the carvone conversion and selectivity. Hydrogen peroxide has a smaller positive effect on the conversion, but at high concentration, H2O2 leads to some decrease in the selectivity. An increase in the oxalic acid concentration has a beneficial effect on the conversion, but does not affect the selectivity.