In this paper, one-dimensional porous Co3O4 nanobelts were synthesized via a facile template-free hydrothermal method and subsequent the thermal decomposition. Their microstructures and morphologies were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and N-2 adsorption-desorption techniques. The results indicate that the reaction parameters such as the molar ratio of Co(NO3)(2)center dot 6H(2)O to C2H4N4, the amount of Co(NO3)(2)center dot 6H(2)O, the hydrothermal temperature and time play crucial rules in controlling the microstructures and morphologies of the as-prepared cobalt precursors. A possible formation mechanism was proposed. Moreover, the obtained porous Co3O4 nanobelts exhibit ethanol gas sensing properties superior to the commercial Co3O4 powders at a working temperature of 200 degrees C, suggesting their potential applications as nanosensors. (C) 2014 Elsevier Ltd. All rights reserved.