We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Mossbauer spectroscopy of three electron-doped perovskites Sr3Fe2MoO9-delta with Fe/Mo = 2 obtained from Sr3Fe2MoO9. The compounds were synthesized by topotactic reduction with H-2/N-2 (5/95) at 600, 700 and 800 degrees C. Above 800 degrees C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group Fm (3) over barm, with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Mossbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 degrees C are only in the high-spin Fe3+ electronic state. (C) 2010 Elsevier Ltd. All rights reserved.