The electrochemical reduction of tinidazole has been carried out in aqueous solution in the pH range 1.8–11.3 by differential-pulse (DP) polarography. Tinidazole exhibits one or two reduction peaks depending on pH. In strongly acidic solution (pH<4.5), one reduction peak was obtained and it was suitable for analytical purposes. A method for the determination of tinidazole by DP polarography in Britton–Robinson buffer of pH 3.0, which allows quantification over the range 0.03–7.30 μg/ml, was proposed. The method was successfully applied to the determination of tinidazole in tablets with mean recovery and relative standard deviation of 98.7 and 3%, respectively. Excipients did not interfere in the determination.