The aim of this work was to find opportunities to reduce the CO-emission in the cement industry. First of all the basics for the cement production are described. It is shown that the demand of energy in the cement industry is very high and that the utilisation of alternative fuels like plastic, cleaning sludge and meat and bone meal is increasing. Moreover possible causes for the rise of CO-emissions are discussed. From this follows that many parameters are responsible for the CO-emission. In the following tests for the determination of the ignition- and burnout-temperature of different fuels are described. Further the influence of non scorched particles in the calcinator was investigated. Finally the oxygen demand and the off-gas composition for the incineration of different fuels were calculated.