Kinetic and mechanistic investigations were made of propane oxidation to acrylic acid over Mo1V0.3Sb0.25Nb0.08On catalyst, calcined at 600degreesC in air, and activated at 500degreesC in O-2/He. The kinetic study allowed determination of the orders of propane disappearance and major products formation, and also emphasised the crucial effect of water on the activation energies of propane and oxygen. Propane and independently propene oxidation at various contact times enabled us to differentiate primary from secondary products and to propose a reaction scheme with three pathways: two major pathways leading to acrylic and acetic acids and a minor pathway leading to propionic acid. It was shown that acetic acid is formed via a route bypassing propene as an intermediate.