The kinetics of the reaction of NO, N2O and CO2 with activated carbon without catalyst and impregnated with a precursor salt of vanadium (ammonium monovanadate) was investigated. The conversion of NO, N2O and CO2 was studied (450-900 degrees C) using a TGA apparatus and a fixed bed reactor. The reactor effluents were analysed using a GC/MS on Line. The addition of vanadium increased carbon reactivity and adsorption at lower temperatures. For NO and N2O conversion the main products obtained were N-2, N2O, CO and CO2 but for CO2 conversion only CO was detected. In situ XRD was a useful tool for interpreting catalyst behaviour and identifying phases present during reaction conditions. The catalytic effect of vanadium can be explained by the occurrence of redox processes in which the catalyst is reduced to lower oxidation states such as V2O5/V6O13. (C)2000 Elsevier Science B.V. All rights reserved.