Chemical looping combustion (CLC) offers the ability to generate energy from fossil fuels inherent capture the greenhouse gas CO2. Oxygen Carriers or O-carriers form the heart of chemical looping processes. They consist of redox couples, Me / MeO-particles, which circulate continuously between the two coupled fluidized bed reactors, and which is thus alternating be in oxidized and reduced state. A better understanding of the effect of oxygen carriers in the application of CL, offers the opportunity to develop better oxygen carriers. Important for the CL and oxygen carriers are not only characteristics as conversion and selectivity, but also mechanical strength to withstand attrition in order to guarantee a sufficient lifetime. In addition, cost and recyclability important. The object of the doctoral is to focus on research in order to increase the resistance of oxygen carriers to attrition forces. In addition, the intention is to make this O-cost carriers economy based on cheap materials. The reuse of O-carriers is a third aspect that gets attention in the dissertation.