A series of Pt/Al2O3 catalysts promoted by metal oxides (Ba, Ce, Co, Cs, Cu, K, La, Mg, Mo, Ti) or noble metals (Ag, Au, Pd, Rh) were prepared and tested for the lean NO, reaction using C3H6 as a reductant. The promoters have a significant effect (beneficial or otherwise) on the activity and temperature range of operation of Pt/Al2O3, but have no significant effect on the N-2/N2O selectivity. The similarity in behaviour of the promoted catalysts and unpromoted Pt/Al2O3 suggests that the reaction mechanism was similar for all the catalysts tested.