Hierarchical mesoporous Co3O4 bundles were obtained by a hydrothermal method combined with a subsequent calcination treatment. During the synthesis of the precursor Co2(OH)2CO3, the versatile ionic liquid 1-butyl-3-methylimidazolium trifluoroacetate performed three roles as the co-solvent, precursor, and template. A supercapacitor based on the as-prepared Co3O4 was fabricated and further evaluated by cyclic voltammetry and chronopotentiometry measurements, which exhibited a specific capacitance of 357 F g−1 at 2 A g−1 after 500 cycles under high loading conditions (approximately 8 mg cm−2). Moreover, the mesoporous Co3O4 was found to maintain 85.5 % specific capacitance with an increase in the current density from 1 to 20 A g−1; this behavior was attributed to the unique structure of the bundles which allowed most of the Co3O4 sheets to efficiently participate in the electrochemical reaction.