In this paper, we present the general equations for a model that describes ion transfer reactions across the oil/water interface assisted by a neutral protonatable ligand in the presence of a buffer solution. Our analysis mainly focuses on the effect of the concentration of the buffered solution and its identity on the voltammetric signal, the pH profile and the buffer capacity of the system. The model was solved using explicit finite difference with exponentially expanding space grid. The results of digital simulations were corroborated by experimental results obtained for the quinine transfer across the H(2)O/1,2-dichloroethane interface in the presence of phosphate buffer, and the corresponding transfer mechanism was analyzed in terms of the current-potential and concentration profiles obtained from the digital simulations. (C) 2010 Elsevier B.V. All rights reserved.