Cd doped porous Co3O4 nanosheets were successfully synthesized via a facile chemical coprecipitation method without using of surfactant or template. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption/desorption isotherms (BET) and X-ray photoelectron spectrum (XPS) for their composition, structure/morphology, and BET surface area, respectively. The nanosheets consisting of nanoparticles prepared here are porous in nature, with average pore sizes of approximately 50nm or smaller. The electrochemical properties of the Cd doped porous Co3O4 nanosheets were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) in 6mol/L KOH solution. The 5% Cd doped porous Co3O4 nanosheets electrode shows the maximum specific capacitance as high as 737F/g at the current density of 1A/g, which is 69% higher than that of the undoped porous Co3O4 nanosheets electrode. Furthermore, it has good specific capacitance retention of ca. 96% after 1000 continuous charge–discharge cycles. It shows a better cyclic stability than undoped porous Co3O4 nanosheets electrode, indicating that the Cd doped porous Co3O4 nanosheets is a promising electroactive material for supercapacitor.