In this study, Co3O4 directly grown on a porous nickel substrate was successfully prepared and characterised as a potential candidate for pseudocapacitor applications. The electrochemical properties of Co3O4 were adversely affected by the sluggish charge transfer at the interface between the electrode and electrolyte and the diffusion of ions from the electrolyte to the interface. These challenges were overcome by the introduction of a high-surface-area Ni substrate for Co3O4, which improves the electrochemical performance of Co3O4; this is indicated by the excellent capacitance and low impedance. This study suggests that the electrochemical properties of several pseudocapacitive oxide materials can be tailored by increasing the surface area of the metal substrate.