The effect of ohmic drop on square-wave voltammetry experiments (SWV) at a liquid-liquid interface is analyzed. The study is based on the distortion of SW voltammetric profiles of the tetraethyl ammonium transfer process across the water/1,2-dichloroethane interface when an uncompensated resistance, R-Omega, is present. Depending on the experimental conditions significant R-Omega values arise as a consequence of the low electrical conductivity of the organic solvent characteristic of these systems, and efficient IR compensation is needed. When R-Omega is not totally removed, a non-linear dependence of peak current (Delta I-p) on the square root of the frequency, an increase of half-peak width (Delta E-p/2) and a shift of peak potential (E,) towards more positive values are observed in the SW profiles. The influence of signal frequency and R-Omega values on SWV parameters (Delta I-p, Delta E-p/2, and Delta E-p/2) is evaluated. (c) 2005 Elsevier B.V. All rights reserved.