A simple and green hydrothermal process has been developed to produce Cu from CuO using cellulose as a reductant under mild hydrothermal conditions. The results showed that CuO was easily reduced to Cu in the presence of cellulose, and a complete conversion of CuO into Cu was obtained at a temperature of 250 degrees C with a reaction time of 1.5 h in 0.50 mol/L NaOH. At the same time, cellulose was converted into value-added chemicals, such as lactic acid and acetic acid. A reaction mechanism for the reduction of CuO to Cu with cellulose as a reductant was also proposed.