The influence of significant ohmic potential drop on diffusion-controlled peak currents in square wave voltammetry at macroelectrodes can be drastically reduced by appropriate choice of the square wave amplitude. This allows direct determinations of unusual high concentrations. The experimental verification of theoretical predictions and the analytical procedure validation are performed using a static mercury drop electrode and various concentrations of Cd(II) in 0.1 or 1 M NaNO3. Diffusion coefficients of Cd(11) and apparent standard potentials of the Cd(II)/Cd(Hg) couple in these media are reported. (C) 2011 Elsevier B.V. All rights reserved.