The SCR of NOx by C3H6 using a 0.1 wt.% Pt/Al2O3 Catalyst has been successfully performed under real diesel gas streams in a power bench.The influence of some experimental variables affecting NOx, CO, and THC conversions, such as hydrocarbon concentration, reaction temperature and space velocity effect, are discussed. 96% NOx conversion has been reached under optimum conditions. The highest NOx conversion level is maintained in the range 250-325 degrees C but slightly higher temperature (350 degrees C) is desired to ensure a stable temperature and complete CO and THC removal. An optimum THC concentration is found (11500 ppm THC), higher THC concentration having a negative effect in the NOx conversion. From experiments performed at different GHSV, the reactor volume required for total NOx removal in a real exhaust stream has been estimated to be 6.5 L Additionally, the effect Of CeO2 on platinum behaviour has been studied, concluding that it enhances N-2 formation as NOx reduction product with respect to N2O, but lowers the platinum activity for NOx reduction and CO and THC oxidation. (C) 2008 Elsevier B.V. All rights reserved,