In this study, first a hydrogel based on sodium alginate and acrylamide was prepared by radical polymerization method and then manganese oxide was formed in its lattice structure and nanocomposite hydrogels were obtained. In the next step, Nanocomposite hydrogels were used as catalysts for the oxidation of alcohols. To evaluate the physical properties and confirm the structure of nanocomposite hydrogels, Hydrogel swelling tests, FT-IR infrared conversion spectroscopy, TGA Thermal gravimetric, SEM Scanning electron microscopy and TEM Transmission electron microscopy were used. The amount of manganese was measured using an atomic absorption spectrometer. Also, factors affecting oxidation reactions such as reaction temperature, amount of catalyst and reaction time were optimized to achieve the highest percentage of conversion of alcohols to aldehydes. Under optimal conditions, the highest conversion percentage of benzyl alcohol was 79% for Benz aldehyde at 80 °C for 24 hours.