The Th 4+ for Sr 2+ substitution in SrCoO 3−δ is found to be an efficient way to stabilize an oxygen deficient perovskite. The structural study reveals a Th 4+ solubility limited to ∼10% so that the chemical formula, Sr 0.9 Th 0.1 CoO 2.79 , is obtained. The comparison to the Y 3+ for Sr 2+ substitution shows that a lower oxygen content is obtained for the former according to the Sr 0.75 Y 0.25 CoO 2.55 formula. The higher oxygen content reached with Th 4+ has a strong impact on the physical properties: Sr 0.9 Th 0.1 CoO 2.79 is an itinerant ferromagnet (T C ∼200K, ρ 5K =2mΩcm) whereas Sr 0.75 Y 0.25 CoO 2.55 is a robust insulating antiferromagnet (T N ∼320K, ρ 5K =10 5 Ωcm). Clearly, the substitution of a tetravalent cation for Sr 2+ appears to be a promising route to synthesize SrCoO 3−δ itinerant ferromagnets without the use of high oxygen pressure nor electrochemical oxidation.