The combined influence of structural factors (Y, Z substituents) on the rate of catalyzed by Z-substituted pyridines reactions of phenyloxirane with Y-substituted N-aroylbenzenesulfonamides in acetonitrile at 293 K was studied. A cross-correlation analysis of the results of a multifactor kinetic experiment was carried out. A polylinear regression, that adequately describes the non-additive effects of substituents Y and Z, was calculated. Due to the interaction of the joint effects of structure, the cross-reaction series exhibits isoparametric properties. The mechanism of the catalytic process has been discussed.