The production of formic acid or formate salts by hydrothermal oxidation of glucose, a model compound of carbohydrate biomass, was investigated in the presence and absence of alkali using a batch reactor with H₂O₂ oxidant. Results showed that glucose was converted into formate salts with an excellent yield of 75% at a mild temperature of 250 °C in the presence of alkali. The results should be helpful to facilitate studies for developing a new green process for the conversion of carbohydrate biomass into formic acid, which can be a potential intermediate for fuels, as well as other value-added products.