[en] The aminolysis reactions of phenyl N-benzyl thiocarbamate with benzylamines in acetonitrile at 50.0 .deg. C are investigated. The reactions are first order in both the amine and the substrate. Under amine excess, pseudo-first coefficient (k_obs) are obtained, plot of k_obs vs free amine concentration are linear. The signs of ρXZ (< 0) are consistent with concerted mechanism. Moreover, the variations of ρX and ρZ with respect to the sustituent in the substrate and large ρXZ value indicate that the reactions proceed concerted mechanism. The normal kinetic isotope effects (k_H/k_D = 1.3 ∼ 1.5) involving deuterated benzylamine nucleophiles suggest a hydrogen-bonded, four-centered-type transition state. The activation parameters, ΔH^† and ΔS^†, are consistent with this transition state structure