Novel hierarchical dandelion-like Co3O4 microspheres have been successively synthesized via a facile solvothermal reaction and subsequent calcination. The calcined products exhibit well-fined dandelion-like morphology with sizes of about 2 mu m. These microspheres are composed of numerous 1D nanorods arranged radially on the surface. The evolution process of dandelion-like microspheres has been investigated, and a possible evolution mechanism has been proposed. When evaluated as a gas sensor, the obtained dandelion-like Co3O4 microspheres exhibit superior ethanol gas sensing performance.