Compositions and methods useful for oxygen sorption and other uses are presented, the compositions being within the general formulas (1), (2), (3), and (4): AxByO3-δ,   (1) AxA′x′ByB′y′O3-δ, and   (2) AxA′x′A″x″ByB′y′B″y″O3-δ,   (3) MOn   (4) and combinations thereof, especially those where the B sites are independently selected from cations of the d block transition metals Cr, Mn, Fe, Co, Ni, and Cu. One desirable set of compositions of the invention are combinations of any one or more of the compounds of generals formulas (1), (2), or (3) with one or more compounds of the general formula (4). In combination with an active support or matrix oxide within general formulas (1), (2), and (3), stability of the binary metal oxides within general formula (4) can be enhanced, while extending the oxygen sorption/desorption capacities of the matrix oxide.