The disclosure provides a metal ferrite oxygen carrier for the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The metal ferrite oxygen carrier comprises MFe.sub.xO.sub.y, where MFe.sub.xO.sub.y is a chemical composition with 1.5.ltoreq.x.ltoreq.2.5 and 3.5.ltoreq.y.ltoreq.4.5 and M is one of Ca, Ba, and combinations thereof. For example, MFe.sub.xO.sub.y may be one of CaFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, MgFe.sub.2O.sub.4. SrFe.sub.2O.sub.4 and combinations thereof. Mixing of the metal ferrite oxygen carrier and the solid carbonaceous fuel generates a product stream comprising at least 50 vol. % CO and H.sub.2. The MFe.sub.xO.sub.y may be supported on an inert support. In an embodiment, the MFe.sub.xO.sub.y comprises at least 30 wt. % of the metal ferrite oxygen carrier the inert support when present comprises from about 5 wt. % to about 60 wt. % of the metal ferrite oxygen carrier.