Catalysts consisting of molybdena supported on different oxides (niobia, alumina, zirconia, silica, magnesia and titania) have been compared for the oxidative dehydrogenation of propane. Of these, titania-supported molybdena was found to be the most selective at isoconversion. A coverage of the titania support greater than a monolayer was necessary in order to achieve an improved selectivity towards propene, with an optimum at approx. 2.4 monolayers. In addition to giving propene and carbon oxides, the majority of the catalysts also had a low selectivity towards oxygenated compounds, mostly acrolein. Some loss of molybdenum was also found with most of the catalysts. Addition of the oxides of vanadium and niobium to the titania-supported molybdena material gave an increase in the rate of the reaction without any loss in the selectivity to propene. This formulation gave a catalyst whose performance was close to a NiMoO4 catalyst examined under similar experimental conditions.