Voltammetry and the EIS technique were applied to study effect of polyether sintanol DS-10 on tin(II) reduction kinetics in strong acidic sulphate solutions containing different halides. Diffusion-controlled Sn(II) reduction was found to be significantly retarded by strong inhibitive adsorption of sintanol. Surface coverage obtained from both impedance and kinetic data may be quantitatively described by means of Frumkin isotherm accounting for interaction between adsorbed particles. Partial suppression of the surface activity of sintanol was observed in the presence of halides. This effect was found to increase in the sequence: Cl- < Br- < I-. © 2004 Elsevier Ltd. All rights reserved.