New catalysts for soot combustion were prepared by impregnation of different supports (SiO2, ZrO2 and ZrO2 center dot nH(2)O) with a LiNO3 solution and then characterized by means of FTIR, XPS, TGA and UV-vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO3/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li2O/supports). Catalysts prepared using LiNO3 are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O-2 mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an "in situ" nitrate ion. (C) 2009 Elsevier B.V. All rights reserved.