Chemical Looping Combustion (CLC) is a second-generation Carbon Capture. The aim of CCS is to store the separated carbon dioxide in underground deposits. The special feature of the CLC method is that the fuel and air are separated from each other. This means that there is no mixing between these gas phases. To achieve that, the required oxygen carrier is circulated between the reactors. The oxygen in the fuel reactor is obtained by the oxygen carrier. That means, that the oxygen carrier is oxidized in the air reactor, thereby the oxygen is transported to the fuel reactor, and reduced in the fuel reactor. After the reaction of the fuel with oxygen, only water vapour and carbon dioxide are produced in the fuel reactor. The water vapour is separated by a condenser and the remaining CO2 is transported to the deposit. In this thesis a copper based oxygen carrier, called Cu15, is analysed. This is an impregnated CuO/Al2O3 compound material and was tested at the Technischen Universität Wien (TUW) at a 120kW pilot plant. The results were compared with previous results. The 120kW system works with a Dual Circulating Fluidized Bed System. During the experiments solid samples of the oxygen carrier were taken at each operating point. This serves to determine the oxidation state of the oxygen carrier. In addition, X-ray fluorescents analysis (XRF) and Thermo gravimetric analysis (TGA) analyses were done. The results of the investigations of the various experiments and the performance of the Cu15 oxygen carrier were discussed in this thesis. The standard conditions for the oxygen carrier were 70kW and 800C. The fuel (natural gas) was taken from the Viennese-Gas-Grid. In addition to this fuel, higher hydrocarbons (propane, pentane) were used and analysed in various mixtures. Those fuels were passed into the fuel reactor in their gaseous phase. All measurements of the operating points were imported, validated and optimized in the simulation program IPSEpro. Furthermore, a sensitivity analysis of small changes of the copper oxide content and the solid sample mass was presented and discussed, because of measurement errors of the oxidation state. In general, the performance of the Cu15 oxygen carrier was good. Full conversion was achieved at higher temperatures. Higher hydrocarbons are having better combustion efficiency at lower fuel reactor specific inventories than natural gas operating points. The sensitivity analysis worked out that the influence of the parameter modification was the highest for the oxygen carrier to fuel ratio ().