Highly uniform urchin-like Co3O4 crystallites were prepared using thermal decomposition of precursor approach. The catalytic activity of prepared crystallites on the thermal decomposition of ammonium perchlorate (AP) shows that Co3O4 plays a catalytic role on the thermal decomposition of AP. The prepared Co3O4 urchin-modified glass carbon (GC) electrode was applied to study the electrocatalytic of H2O2. The results demonstrate that Co3O4 urchin have great potential in sensor and biosensor applications. (C) 2010 Published by Elsevier B.V.