The reaction rates of para-substituted benzoyl chlorides with substituted pyridines have been measured employing the conductometry method in acetonitrile, and pseudo-first order and second order rate constants are determined at various pressures and temperatures. The activation parameters (${Delta}V^ eq, {Delta}{eta}^{ eq}, {Delta}H^{ eq}, {Delta}S^{ eq} {Delta}G^{ eq}$) and the Hammett ρ-values are determined from the values of rate constants. The values of △${Delta}V^ eq, {Delta}{eta}^{ eq}and {Delta}S^{ eq}$ are all negative. The Hammett ρ-values are negative for the nucleophile (ρ$_X$), and positive for the substrate (ρ$_Y$) over the pressure range studied. The results of kinetic studies for pressure and substituent show that these reactions proceed in typical S$_N$2 reaction mechanism and in bond formation favored with elevating pressure.