The effects of partial substitution of Sr2+ by Ca2+ and Ba2+ on the A-site of oxygen deficient perovskites, Bi0.15Sr0.85-yAeyCo1-xFexO3-?, where y = 0.29 for Ae = Ba and y = 0.17 for Ae = Ca, and 0.0 ? x ? 1.0, have been investigated. The differing ionic size of the Ca2+ and Ba2+ cations influences both the crystal structure and the properties of the materials. The smaller Ca2+ cation favoured formation of an oxygen vacancy ordered perovskite superstructure (I4/mmm, a = 2ap, c = 4ap), meanwhile the presence of the larger Ba2+ cation promoted a disordered simple cubic structure (Pm-3m, a = ap) that was also found for all Fe containing samples, i.e. x ? 0.25. The samples were studied with PXRD, NPD, TGA, HREM and magnetic susceptibility measurements. All as-prepared samples exhibited long range G-type antiferromagnetic ordering. The effect of oxygen annealing was dramatic for the Bi0.15Sr0.68Ca0.17Co1-xFexO3-? series with a disappearance of magnetic order for x ? 0.25 linked to increasing spin glass properties. The oxygen content of the Bi0.15Sr0.56Ba0.29Co1-xFexO3-? as-prepared materials was generally higher than their Ca substituted counterparts, and the long range antiferromagnetic order was more resistant to oxygen annealing.