Blue-color emitting material, CaMgSi2O6:EU2+ (CMS:Eu2+), was synthesized by a normal solid state reaction using CaCO3, MgO, SiO2 and EuF3 as starting materials. The Rietveld method was employed to quantitatively determine the structural parameters of synthesized CMS:Eu2+. The structural parameters for CMS:Eu2+ were successfully determined by Rietveld refinement using X-ray powder diffraction data. The final weighted R-factor, Rw,, was 9.22% and the goodness-of-fit indicator, S(= R-wp/R-e), was 1.45. The synthesized sample consisted of CMS:Eu2+ and SiO2 (cristobalite) phases with refined phase fractions of 89.18(1)% and 10.82(2)%, respectively. Doped EU2+ ions occupied the Ca sites (4e) and replaced 1.0% of the Ca2+ ions. The refined model of CMS:Eu2 + describes a structure in monoclinic space group C 2/c with Z = 4, a = 9.7474(2)angstrom, b = 8.9384(2) angstrom, c = 5.2490(1) angstrom and beta = 105.87 (1)degrees. (c) 2005 Elsevier B.V. All rights reserved.