We report one-step conversion of dimensionally mixed ternary nanocomposite from zerodimensional (0D) cerium oxide (CeO 2 ), one-dimensional (1D) carbon nanotube (CNT), and two-dimensional (2D) reduced graphene oxide (RGO) nanomaterials by chemical precipitation method. The RGO/CNT/CeO 2 ternary nanocomposite showed excellent electrochemical performance (electrical double layer capacitor properties) in aqueous electrolyte followed by long term cyclic stability, and high energy density compared to its binary counterparts.