Partial oxidation of propane was performed over V2O5-P2O5-based catalysts in the presence of a large excess of oxygen at 350 to 400-degrees-C. The main products were acrylic acid, acetic acid, and carbon oxides. Of the V2O5-P2O5 binary oxides, the best catalyst performances were obtained at a P/V atomic ratio of 1.00; the presence of an excess of phosphorus with respect to the P/V = 1.00 composition induced a large decrease in both the activity and selectivity to form acids. Incorporation of H3PMo12O40 to a P/V = 1.00 oxide enhanced greatly the formation of acetic acid.