In a previous paper [J. Electroanal. Chem. 578 (2005) 159] we have presented the general equations for a model of ion transfer reactions across the oil vertical bar water interface assisted by a neutral protonatable ligand. Our analysis focused mainly on the effect of water autoprotolysis on transfer processes. In this second part, cation transfer assisted by a protonatable ligand is described. The competitive reaction for a ligand between metal cation and proton is presented. The results are analyzed for different zones determined by the cation/ligand and proton/ligand concentration ratios. (c) 2005 Elsevier B.V. All rights reserved.