In recent years, spinel-type compounds have attracted great interest because of their gem-like qualities. However, little is known of their gas sensing properties. We report, in this paper, on a self-assembly method to prepare porous ZnCo2O4 (ZCO) nano/microspheres by a facile one-step solvothermal process and subsequent annealing. Abundant techniques were used to characterize the morphology and structure of the as-obtained compounds. Our data indicate that the hierarchical nano/microspheres are constructed from numerous nanoparticles primarily, which have a higher specific surface area (ca. 77.3 m(2) g(-1)) and are of uniform diameter (ca. 1 μm). To demonstrate their potential application, gas sensors based on the as-synthesized ZCO nano/microspheres were fabricated to test their sensing performance, whose sensing behaviours correspond to p-type semiconductors. The test results also indicate that porous spinel-type compounds have an excellent kinetic response to ethanol at an operating temperature of 175 °C and a superior selectivity. As such, hierarchical porous ZnCo2O4 nano/microspheres will hold promising potential in the gas sensor field.