SrTiO3 based mixed oxides with perovskite-like structure were prepared by sol-gel citric method. The potassium promoter (2 mol%) was introduced into the material during the synthesis as well as via postimpregnation, leading to two different catalytic systems: Sr0.8K0.2TiO3, and K/SrTiO3, respectively. The obtained materials were characterized by XRD. Sr. cyclohexanol (CHOL) decomposition, XPS and SR-TAD (species resolved thermal alkali desorption), whereas their catalytic activity in soot combustion was examined in laboratory conditions. It has been shown that introduction of potassium substantially promotes the catalysts activity, which can be gauged by the lowering of the soot ignition temperature by 100 degrees C for K/SrTiO3 and 120 degrees C for Sr0.8K0.2TiO3. The effect is discussed in terms of potassium volatility, work function changes and basicity, however the experimental data revealed that the indirect effect is also involved. The most active system was obtained when potassium partially substituted strontium in the perovskite structure. As a consequence oxygen vacancies were created, leading to higher concentration of basic surface oxygen species. Since in the case of Sr0.8K0.2TiO3. IC ions are located in the structural positions, this catalyst apart from the highest activity exhibits also the highest potassium stability. (c) 2010 Elsevier B.V. All rights reserved.