Controlled synthesis of metal oxide semiconductors for applications in detection of toxic gas has attracted interests from researchers worldwide. In this work, the authors report on the hydrothermal synthesis of nanostructured Co3O4 for Benzene gas sensing ap .ications. Different morphologies of the Co3O4 such as nanoparticles, nanorods, and porous plates were fabricated by varying the synthesis conditions. Microstructure and characteristics of the synthesized materials were investigated by means of XRD, SEM and TEM images. Gas-sensing measurements demonstrated that the nanorod structure of the Co3O4 exhibited the higest response to Benzene compared with other morphologies.