The electrochemical behaviour of Co3O4 with sodium is reported here. Upon cycling in the voltage window of 0.01-3.0 V, Co3O4 undergoes a conversion reaction and exhibits a reversible capacity of 447 mA h g(-1) after 50 cycles. Therefore, nanostructured Co3O4 presents feasible electrochemical sodium storage, offering possibilities to develop new anode materials for sodium-ion batteries.