A class of mixed oxide catalysts comprising Mn-containing oxides, alkali metals or compounds thereof, and at least one member of the group consisting of oxides of Ti, mixed oxides of Ti and Si, and mixed oxides of Ti and at least one alkaline earth metal. In the more preferred embodiments, the third component serves as a carrier for the Mn and alkali metal components. The composition preferably comprises a major amount of the carrier material and minor amounts of the other components. The compositions are useful for hydrocarbon conversion, methane conversion, and oxidative dehydrogenation processes characterized by formation of coproduct water.