Catalytic hydrocarbon combustion is a technologically important, but still relatively poorly understood reaction. To shed more light on the role of various physical and chemical characteristics of the catalyst on its activity for hydrocarbon combustion, La1-xSrxM1-yM'O-y(3-delta) perovskites (M and M' represent transition metals) were used as a model system. Four representative compositions were prepared and fully characterized by different methods and their activity was determined in methane and propane combustion. Oxygen desorption reflecting oxygen mobility is mainly a function of composition, more or less independently from specific surface area (SSA). On the other hand, the results confirm that SSA is the important factor determining the high activity. Yet, in these oxide type catalysts (perovskites) the loss of activity due to lower SSA, resulting from aging at elevated temperatures, seems, to a large part, be compensated for by fast oxygen mobility assured in oxygen nonstoichiometric compositions. (C) 2003 Elsevier B.V. All rights reserved.