The catalytic efficiency of V2O5 supported on hydroxyapatite in controlled oxidation of n-pentane to phthalic anhydride and maleic anhydride is investigated as function of flux rates of the reactants and temperature in the gas- phase in a fixed- bed stainless steel microreactor under steady state conditions. The hydroxyapatite was prepared by co-precipitation and the loaded catalysts by wet impregnation using NH4VO3 solution. Selectivity towards the products was influenced by the total flow rate, reaction temperature and V2O5 loadings. Good selectivities towards the anhydrides (MA 40% and PA 25%) is obtained with 5.0 and 7.5 wt.% of V2O5 at 360 degrees C.