An underwater impulse discharge was used for synthesis tungsten trioxide nanoparticles. The chemical composition and morphology of obtained particles were studied by using X-ray diffraction spectroscopy and electron microscopy. The dynamic light scattering was used to measure the average particle diameter and zeta-potential. It was found that a monoclinic modification of tungsten trioxide was formed with an average particle diameter of about 60 nm. The photocatalytic performance of WO3 was estimated through the degradation of Rhodamine B under dark and UV irradiation conditions. The powder of WO3 exhibited great photocatalytic activity for photodegradation of Rhodamine B of 100% under UV irradiation for 50 min.