The aim of this work was to study the influence of the reaction temperature on the efficiency of the electrochemical promotion to improve the catalytic performance of a Pt impregnated catalyst for the reduction of nitrogen oxides under lean burn conditions. Open circuit catalytic and potential measurements were carried out in order to explain the potentiostatic behaviour of the electrochemical catalyst under different reactions temperatures. At low temperature (220 degrees C), the application of negative polarization increased the NO reduction rate by a factor of 1.4 (electrophilic behaviour). But as the reaction temperature was higher, the efficiency of electrochemical promotion to improve the catalytic activity decreased, even leading to a poisoning effect at 300 degrees C. This progressive suppression of the promotional effect was due to an increase with temperature of the oxygen coverage on the catalyst, which led to a C3H6 adsorption inhibition. Nevertheless, at all explored reaction temperatures, the presence of sodium promoter gave a large increase in N-2 selectivity, even reaching 90%. These results demonstrated that electrochemical promotion is a suitable technique to improve the catalytic performance of Pt catalyst for the practical development of HC-SCR process to removal nitrogen oxides. (c) 2007 Elsevier B.V. All rights reserved.