Two series of mixed oxides with formula [Eu2-xMx][Sn2-xMx]O7-3x/2 (M = Mg or Zn) have been synthesized. The study by X-ray diffraction and Fourier transform infrared spectroscopy shows that the solids obtained are new non-stoichiometric solid solutions with the pyrochlore type structure. For both series a decrease of the cell parameter is observed when the degree of substitution, x, increases. The structural refinements (X-ray studies) were achieved in the space group Fd-3m, no. 227 (origin at center-3m) by using the Fullprof software. The Rietveld refinements show that the divalent cations M2+ (Mg2+, Zn2+) substitute isomorphically for Eu3+ and Sn4+ ions producing vacancies in the anionic sublattice. (C) 2009 Elsevier Ltd. All rights reserved.