The assisted transfer of proton by interfacial complexation with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone (APPT) has been investigated at the micro interface of two immiscible electrolyte solutions (ITIES) hosted by a 25 pm diameter pipette. Thermodynamics of proton transfer has been investigated by using cyclic voltammetry. The dependence of half wave potential on the ligand concentration suggests that the equilibrium is effectively displaced towards a 1:1 (proton:ligand) stoichiometry, with a formation constant of 6.3 x 10(9). The formal Gibbs energy of proton transfer, the diffusion coefficient of proton in aqueous solution and diffusion coefficient of APPT in organic phase have been evaluated. The kinetic parameters of ion transfer process have also been studied by micropipette voltammetry. (C) 2009 Elsevier B.V. All rights reserved.