The catalytic behavior of a series of VOx/alpha -Al2O3 catalysts for the partial oxidation of methane has been evaluated. Samples with different vanadia loading were prepared from NH4VO3 and V(AcAc)(3). Characterization performed by TPR and oxygen uptake measurements indicates that different VOx species are present on the samples. The catalytic patterns indicate that each V-surface species possesses different activity and selectivity. Isolated vanadates are the most active and selective towards HCHO, while V2O5 crystallites are detrimental to the catalytic performance.