Abstract:Molybdenum trioxide was synthesized by using hydrothermal method and (NH4)2Mo4O13·H2O as raw material. The effects of different pH value, hydrothermal reaction time, filling degree and calcination temperature on the MoO3 powder were studied. The structure and morphology of the samples were characterized by XRD and SEM. Results show that, when the pH value is 1, the hydrothermal reaction time is 16 h, the filling degree is 90% and the calcination temperature is 550 ℃, MoO3 powder has uniform size, smooth surface and good dispersion; The crystal type of MoO3 is changed during the calcination process, and all the MoO3 crystals change from h-MoO3 to α-MoO3 when the calcination temperature reaches 350 ℃.