Chemical looping is an efficient, economic and sustainable means for electricity and/or chemicals production with inherent CO2 sequestration ability. Oxygen carriers play a crucial role in the successful operation of a chemical looping system as their physical and chemical properties dictate the fuel conversion efficiency of the system. They are expected to undergo multiple redox cycles while maintaining their reactivity and mechanical strength in order to improve the overall process economics for commercial viability. This research investigates the behavior of oxygen carriers under different reactive conditions and evaluates their feasibility for biomass chemical looping systems. The reduction kinetics of OSU’s iron titanium complex metal oxide (ITCMO) oxygen carrier particles are investigated at elevated pressures with H2 and CH4 for application in OSU’s Shale gas-to-Syngas process. Under CH4, there is almost a 5-fold increase in the reduction rate with an increase in pressure from 1 to 10 atm. Solid characterization revealed increased porosity and surface area at elevated pressures. Faster reaction kinetics at higher pressures can translate into increased processing capacity, reduced reactor sizing, and decreased capital costs. The steam to H4 conversion efficiency of Fe2O3 based oxygen carriers using Al2O3, MgAl2O4 and TiO2 as support materials is investigated in a fixed bed for chemical looping H2 generation. All supported-Fe2O3 based oxygen carriers exhibited >70% steam conversion, close to thermodynamic predictions. Due to its ability to not form complexes with the active material, MgAl2O4 -supported Fe2O3 was selected for further investigation. Thermogravimetric studies with steam oxidation exhibited excellent recyclability and no significant drop in reactivity. MgAl2O4 -supported Fe2O3 also exhibited enhanced steam oxidation kinetics at elevated pressures. Tar derived from biomass pyrolysis is a major concern for biomass thermochemical conversion processes. For biomass fueled chemical looping processes, it is important to evaluate effects of tars on the oxygen carriers. Fixed bed experiments demonstrated that OSU’s ITCMO oxygen carriers have reasonable reactivity for cracking most biomass-derived tar components. To further enhance the tar cracking ability of Fe2O3 -based oxygen carriers, they are combined with traditional tar cracking catalysts. Based on thermogravimetric reactivity and fixed bed tar cracking experiments, NiO is selected as an additive for Fe2O3 -based oxygen carriers for biomass chemical looping systems. The outcomes from this research will help in the development of economic and efficient oxygen carriers for the commercialization of the various chemical looping applications.