A facile one-pot microwave assisted hydrothermal synthesis of hierarchical cobalt oxide/reduced graphene oxide composite electrode for high-performance supercapacitors

•Hierarchical Co3O4/rGO nanocomposites are synthesized by a facile one-pot microwave-assisted hydrothermal approach.•The size of Co3O4 nanoparticles is effectively reduced to 8.5 nm by 35 wt% addition of rGO.•Co3O4/rGO composites exhibit a specific capacitance of 1031 F g−1 at 1 A g−1, and 78% capacitance retention at 10 A g−1.•The approach can be extended to synthesize other TMOs and carbonaceous nanocomposites for superior electrode materials.