Co2P nanocomposites were successfully synthesized via a facile hydrothermal method. The microstructure, morphology and elemental composition were examined by XRD, SEM, TEM and XPS. The effects of synthesis temperature and reaction time on the sensing properties of Co2P nanocomposites were analyzed. The Co2P sensor at 200[Formula: see text]C and 3 h reaction condition exhibited optimum sensitivity toward 100 ppm ethanol. In comparison with other gases, ethanol possesses good selective characteristics at optimal operating temperature of 160[Formula: see text]C, which greatly reduce energy consumption. The above results showed that Co2P nanocomposites have the potential application as an effective sensor for ethanol detection.