Particles with Mn/(Mn + Fe) = 0.55–0.87 show good performance for CLC with solids. (MnxFe1−x)Ti0.15Oz oxygen carriers can show permanent magnetic properties. The reactivity with fuel gases (CH4, H2 and CO) increases with the Mn content. The magnetic permeability increases as the Mn content decreases. Material with Mn/(Mn + Fe) = 0.55 is preferred considering its reactivity and magnetism.