We have investigated the effect of Fe doping on the structural and electrical properties of the double perovskite oxide Sr2Mg1-xFe5MoO6-delta (x = 0, 0.2, 0.5). The structure of the Fe doped compounds is tetragonal, unlike the triclinic undoped compound. The Fe doping favors the reduction of Mo6+ to Mo5+, which plays a vital role in determining the electrical properties. The conductivity increases with increasing Fe content. The samples were found to be stable in both oxidizing and reducing conditions. (C) 2013 Elsevier B.V. All rights reserved.