Red phosphors EuW 2 O 6 (OH) 3 were synthesized via a facile hydrothermal method at different pH values (1, 2, 3, 4, 5, 6 and 7) at 180°C for 24h. The XRD patterns indicate that as-obtained phosphors exhibit monoclinic phase. The SEM results show that the as-obtained phosphors exhibit micro-spherical morphologies. The emission spectra under 394nm excitation exhibit dominant peaks centered at 617nm. pH value has a strong effect on the phosphor morphology and the emission intensity. The strongest 617nm red emission was obtained at pH6. The influence of morphology and crystal size on the intensity of red emission were discussed. The as-obtained micro-phosphors are potential candidate for red-emitting LED phosphors.