Vanadium oxide-based catalysts promoted with KCl and a transition metal chloride (M = Cu, Ce, Fe, Co, Zn) have been investigated in the oxidation of diesel soot and characterized by thermal analysis techniques, such as temperature-programmed reduction (TPR) and differential scanning calorimetry (DSC). Aim of the study was to acquire information on the reaction mechanism of the catalytic soot combustion over these catalytic systems. Data presented suggest that the activity of investigated catalysts is correlated to their reducibility which favor the redox activity of the active vanadium species. The formation of eutectics between components of the catalyst also occur improving the catalyst-carbon contact.