In one embodiment described herein, fuel may be converted into syngas by a method comprising feeding the fuel and composite metal oxides into a reduction reactor in a co-current flow pattern relative to one another, reducing the composite metal oxides with the fuel to form syngas and reduced composite metal oxides, transporting the reduced composite metal oxides to an oxidation reactor, regenerating the composite metal oxides by oxidizing the reduced composite metal oxides with an oxidizing reactant in the oxidation reactor, and recycling the regenerated composite metal oxides to the reduction reactor for subsequent reduction reactions to produce syngas. The composite metal oxides may be solid particles comprising a primary metal oxide and a secondary metal oxide.