Two dimensional (2D) porous cobalt oxide (Co3O4) nanoflake (CONF) arrays are prepared by a facile sonochemical synthesis followed by calcination at 300 °C for 3 h. The successful synthesis and phase purity of CONFs were confirmed using X-ray diffraction (XRD) and Raman spectroscopy. Field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) analyses confirmed the porous flake-like structure of Co3O4. The performance of the CONFs is evaluated for energy storage application. The electrochemical performance in standard three electrode cell system revealed a high redox behaviour of CONFs which reveals its battery grade behaviour. In order to fabricate the supercapattery, CONFs-based electrode is employed as a positive electrode while activated carbon based electrode is used as negative electrode. Supercapattery device showed an excellent performance in terms of specific capacity (108.8C/g), energy density (23.7 Wh/kg) and power density (307 W/kg). The enhanced electrochemical performance was attributed to the unique 2D porous structure of Co3O4. Additionally, supercapattery showed excellent cyclic stability over 2500 cycles by maintaining 88.5% of its initial specific capacity value. Display omitted •Porous Co3O4 nanflakes were prepared by sonochemical method.•Structural and morphological characterizations were done.•Electrochemical performance of Co3O4 nanoflakes was done for energy storage.•Co3O4 nanoflakes based supercapattery gave enhanced electrochemical performance.