Ion-transfer voltammetry of organic amines at an organic solvent/water (O/W) interface is studied. A theoretical equation of the current vs. potential curve of amines at a dropping electrolyte electrode is derived. The partition processes of both protonated and neutral forms of amine at O/W interface are taken into account. Kinetics of the protonation reaction between the neutral and protonated forms in W phase is also taken into account using the reaction layer theory. The theoretical prediction is in good agreement with the experimental results obtained with procaine at nitrobenzene/water interface using a dropping electrolyte electrode. Ion-transfer voltammetry and polarography is useful for studying the partition of amines between O and W phases in both neutral and protonated forms and the protonation reaction of amines in W phase as well. (C) 1998 Elsevier Science Ltd. All rights reserved.