In this work, rhodium nanoparticles were synthesized using hydrothermal method that is simple and easy to manipulate reaction and use nontoxic supercritical water. The rhodium nanoparticles were formed in uniform size and shape. These Rh NPs also acted as a efficient heterogenous catalyst in reduction of 4-nitrophenol to 4-aminophenol. Moreover, the rhodium nanoparticles can be recycled without any loss in catalytic activity, and showed highly catalytic activity for various nitroarenes. Therefore, this method will contribute greatly to the development of environmental field and be suitable for use in the industry.