Metal oxide catalysts

Solid oxide solutions of the formula La.sub.1-x Sr.sub.x CrO.sub.3-.differential. have been found to exhibit suprisingly high specific activity as catalysts for oxidation and hydrogenation reactions. The oxide solutions can be utilized in particulate form or applied as films to the surfaces of refractory substrates. The oxide solution catalysts are expected to be a viable alternative to the noble metal catalysts now used commercially for treatment of combustion chamber exhaust gases to reduce environmental pollutants.