Polycrystalline powders of rare earth molybdates R2Mo4O15 (R = La, Gd and Y) with and without Eu3+ ion-doped were synthesized by using a solid-state reaction. The structure, UV-visible diffuse reflectance spectra, photoluminescence spectra and their temporal decay of these compounds were characterized. The diffuse reflectance spectra indicate that all the compounds have strong absorption of near-UV light due to the optical excitation of the MoOx groups within the host lattices. Upon a near-UV light excitation, Y- and Gd-contained host lattices show very weak luminescence, while La-contained sample does not luminesce. When activated by Eu3+ ions, all the compounds show intense red luminescence mainly originated from Eu3+ ion D-5(0)-F-7(J) transitions. The luminescence can be obtained by exciting either into the host lattices or into Eu3+ ion f-f transitions indicating efficient energy transfer from host matrices to dopant Eu3+ ions. The photoluminescence properties of the compounds were studied as a function of the host lattice structure as well as the Eu3+ ion concentration. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.049203jes] All rights reserved.