Sr 3 FeTaO 7 and Sr 4 FeTaO 8 , the n=2 and n=1 member of Ruddlesden–Popper (RP) phases in a double perovskite family Sr n+1 (Fe,Ta) n O 3n+1 , have been synthesized by solid state reaction at 1350 °C in air. The crystallographic study shows that both compounds adapt typical tetragonal RP structures in the space group I4/mmm with the lattice parameters, a=3.9650(1)Å, c=20.5560(2)Å for Sr 3 FeTaO 7 and a=3.9493(1)Å, c=12.6641(2)Å for Sr 4 FeTaO 8 . Similar to Sr 2 FeTaO 6 , Fe 3+ and Ta 5+ ions are randomly distributed in a single B-site in these structures. At low temperature, both Sr 3 FeTaO 7 and Sr 4 FeTaO 8 exhibit antiferromagnetic interactions, but no long-range magnetic ordering was observed.