Large-scale micro- and nano-sized Eu3+-doped gadolinium tungstate and molybdate Gd2MO6:Eu3+ (M=Mo, W) red phosphors with special morphologies have been successfully prepared via an efficient molten salt synthesis (MSS) method at 950°C for 6 h using NaCl and as the reaction medium. The results of X-ray powder diffraction patterns indicate that Gd2MoO6 and Gd2WO6 have monoclinic structures. The scanning electronic microscope and transmission electron microscope studies revealed that the samples of Gd2WO6:Eu3+ and Gd2MoO6:Eu3+ phosphors obtained by the MSS method in NaCl medium have a sphere-like morphology, and the corresponding samples obtained in KCl medium have rod-like morphologies. For the Gd2MoO6:Eu3+ phosphor obtained in NaCl and KCl media, the sphere-like particles had an average grain size of ∼100 nm, and the size of the rod-like particles ranged from 200 to 400 nm in length, and ∼150 nm in width, respectively. Compared with the same products obtained by the solid-state reaction we had reported, the luminescent properties of Gd2MO6:Eu3+ (M=Mo, W) are largely dependent on their morphology and crystal size prepared using different fluxes of NaCl and KCl. The reaction time and temperature also play an important role in the crystallization of the samples.