Alumina supported phosphovanodomolybdic acid and alumina supported phosphovanodomolybdic acid-transition metal ions (M: Fe3+, Co2+, or Ni2+) were prepared by impregnation. The thermal decomposition, in situ at 400 degrees C, of supported catalysts showed the formation of V2O5, P2O5, MoO3 and MoO3, CoMoO4, Mo0.3V0.7)(2)O-5 phases, on the alumina surface, in the presence of H4PMo11VO40/alpha-Al2O3 and H4PMo11VO40-Co/alpha-Al2O3, respectively. The catalytic activity of alumina-supported catalysts was evaluated in the reaction of propane oxidation at 380 and 400 degrees C. The addition of transition metal increases the conversion and changes the reaction products distribution. The reaction conditions (temperature and propane/oxygen ratio) have also modified the behaviour of the studied catalysts.