Manganese-tin bimetallic oxide (MnSnO) is synthesized by solvothermal approach using manganese acetate, stannic chloride as precursors and urea as precipitating agent in aqueous media. The crystallinity, purity and lattice parameters of the product are analyzed by X-ray diffraction analysis. Morphology of the product is analyzed with the help of Scanning electron microscopy. The synthesized product is used as fuel additive and catalyst. Synthesized MnSnO is used as catalyst for degradation of an organic dye Congo red in aqueous medium. Catalytic degradation is monitored at different concentrations of catalyst and hydrogen peroxide. Moreover the role of MnSnO as additive in diesel fuel is studied. The efficiency of modified fuel is analyzed by studying the different parameters such as flash point, fire point, cloud point, pour point, calorific values and specific gravity. The values of these parameters change significantly by changing the dosage of additive.