Abstract: An atmospheric pressure glow discharge was ignited between a molybdenum anode and the water surface of a cathode for the synthesis of MoO₃ powders. The action of glow discharge leads to the non-equilibrium evaporation of water, sputtering of the metal anode and formation of molybdenum (VI) oxide, which deposited on the anode. The chemical composition and morphology of the obtained powder were performed by using x-ray diffraction spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. It was found that the synthesized powders are pure α-MoO₃. The possible mechanism of the formation of molybdenum trioxide during glow discharge treatment was described. The photocatalytic performance of MoO₃ was estimated through the degradation of Rhodamine B under dark and UV irradiation conditions. Orthorhombic MoO₃ exhibited the best photocatalytic activity for the photodegradation of Rhodamine B of 100% under UV irradiation for 15 min.