3D mesoporous hybrid NiCo2O4@graphene nanoarchitectures were successfully synthesized by a combination of freeze drying and hydrothermal reaction. Field-emission scanning electron microscopy (FESEM) and TEM analyses revealed that the NiCo2O 4@graphene nanostructures consist of a hierarchical mesoporous sheet-on-sheet nanoarchitecture with a high specific surface area of 194 m 2 g-1. Ultrathin NiCo2O4 nanosheets, with a thickness of a few nanometers and mesopores ranging from 2 to 5 nm, were wrapped in graphene nanosheets and hybrid nanoarchitectures were formed. When applied as electrode materials in supercapacitors, the hybrid NiCo 2O4@graphene nanosheets exhibited a high capacitance of 778 F g-1 at a current density of 1 A g-1, and an excellent cycling performance extending to 10000 cycles at a high current density of 10 A g-1. This journal is © the Partner Organisations 2014.