Chemical Looping Combustion (CLC) is a two-step gas combustion process that produces a pure CO2 stream, ready for compression and sequestration. A solid oxygen carrier (OC) circulates between two reactors and transports oxygen from the combustion air to the fuel. Since the fuel is not mixed with air, the subsequent CO2 separation process is not necessary. A key aspect in CLC process using refinery and industrial gases is to know the behavior of the oxygen carriers under real gas mixtures that contain impurities as for example, sulfur and light hydrocarbons. The objective of this work was to analyze the effect of these impurities on the behavior of a Nickel-based oxygen carrier prepared by dry impregnation on α-Al2O3. The tests were carried out in a continuous 500 Wth CLC plant. Based on these results, important conclusions with respect to design of CLC plants are derived, which can help to the development of this technology in the near future.