The effect of uncompensated ceil resistance on current-potential curves obtained with the potential sweep method is presented for simple electrochemical reactions in conditions of a constant ionic activity and with the product entirely adsorbed on the electrode surface under either quasiequilibrium or Tafel conditions. First and second order processes are considered. Results obtained for the latter are referred to the electrochemical reduction of platinum oxide film in 1N sulphuric acid at room temperature.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas