The use of platinum supported on activated carbons as catalysts for the selective catalytic reduction of NOx (NO + NO2) using C3H6, under lean-burn conditions, has been investigated. Two different platinum precursors (H2PtCl6 and [Pt(NH3)(4)]Cl-2) and three commercial activated carbons have been used to prepare the catalytic systems. Temperature programmed reaction (TPR) and isothermal experiments, using 1000 ppm C3H6, 1000 ppm NO and 5% O-2 in He, have been carried out to study the effect of different variables such as platinum precursor, metal dispersion and support properties. The results have been compared with those of conventional platinum supported on alumina catalysts, platinum precursors and metal dispersion have no effect on catalyst performance. However, two great advantages have been found using activated carbons as support. First, a NOx conversion increase, in the experimental conditions used, and second, a decrease in the temperature corresponding to the maximum conversion of NOx. (C)2000 Elsevier Science B.V. All rights reserved.