The diesel soot combustion was studied using catalysts prepared by impregnation with lithium nitrate and/or gold on zirconium oxide (ZrO2), hydrated zirconium oxide, and silica (SiO2). Catalysts were characterized by elemental analysis, atomic absorption spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Measurements of catalytic activity were performed in a fixed bed reactor with a NO/O-2 feed. The NO reacts with the Li2O generating "in situ" lithium nitrate that participates in the oxidation of diesel soot and accelerates the reaction rate. All catalysts containing lithium nitrate exhibit a good activity for soot oxidation, and the gold addition substantially increases selectivity to CO2.