In this paper, effect of NH4Cl flux concentrations (0, 1, 2, 3 and 4 wt%) on the crystal structure, morphology and photoluminescent properties of Sr2SiO4:Eu3+ phosphors synthesized by a microwave sintering at 1200 degrees C for 1 h was investigated and discussed. X-ray powder diffraction analysis showed the crystal structure was not affected and the pure Sr2SiO4 phase was formed without second phase or phases of starting materials when adding with the NH4Cl flux. The SEM images indicated that increase of the NH4Cl flux enlarged the particle size of the phosphor particles. The photo-luminescence results showed the addition of 1 wt% NH4Cl flux much improved the emission intensity at lambda(em) of 617 nm as the excitation spectrum at lambda(ex) of 395 nm. The decay times of Sr2SiO4:Eu3+ phosphors with different NH4Cl flux concentrations were obtained around 2.47-2.52 ms. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.