We report a facile soivothermal method for producing Co/C microspheres composed of nanosheet structures in a mixture of water and ethylene glycol. The morphology and cobalt loading of the Co/C microspheres can be controlled by adjusting the solvent composition. The Co/C microspheres obtained in the water-ethylene glycol mixture and calcined at 700 degrees C were very active for the hydrogenation of chloronitrobenzene (CNB), with 98% CNB conversion and 97% selectivity to o-chloroaniline at 2.0 MPa and 140 degrees C. In the hydrogenation of p-CNB and m-CNB, the catalyst showed a conversion of >= 97% and a selectivity of 99% to the corresponding chloroanilines. (c) 2007 Elsevier Inc. All rights reserved.