Co-doped ZnO hierarchical aggregates have been successfully synthesized by a simple one-pot method. SEM and TEM results show that the aggregates have branch-like morphology and well dispersed microstructure. SAED shows that the aggregates are single crystalline and EDX reveals similar to 5 at% cobalt doping content. XRD results indicate that the doped aggregates are of higher crystal quality compared to the pure ZnO hierarchical aggregates prepared by similar method. XPS results reveal that there are abundant adsorption sites on the surface of the aggregates. More importantly, the gas sensor made of Co-doped ZnO hierarchical aggregates shows significantly higher gas response than that from pure ZnO hierarchical aggregates. In addition, it also shows good stability, faster response and recovery speed and a high selectivity for alcohol vapor. (C) 2014 Elsevier B.V. All rights reserved.