In this paper, cobalt(II) oxide (CoO) has been used as an anode catalyst in a direct borohydride fuel cell (DBFC). The microstructure of CoO has been characterised by X-ray diffraction. The cell performance and short-term performance stability of the DBFC using the CoO as anode catalyst have been investigated. At the optimum conditions, the maximum power density of 80 mW cm(-2) has been achieved at 30 degrees C for this cell without using any precious metals and ion exchange membranes. Results from XRD. TEM, and XPS analysis confirm that the good performance of the fuel cell is attributed to the co-operation of CoO and CoB which formed from CoO during the operation. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.