The scope of this thesis is to analyse the operating behaviour of oxidation catalysts to reduce the emissions of carbon monoxide in the exhaust gas of a rotary kiln for producing cement clinker. The catalysts of different manufacturers are tested at an experimental plant which is situated in the low dust area at the cement plant in Rohrdorf. First of all the principles of the catalytic oxidation of carbon monoxide and possible deactivation mechanisms of the catalysts are explained. The tests give an overview of the performance of the catalysts which are currently available on the market. All of these catalyst were deactivated fast. Based on this benchmark new catalysts are developed step by step in collaboration with one catalyst manufacturer. These catalysts should be less susceptible to deactivation by various compounds of the flue gas. The continued test at the experimental plant showed that currently there is no catalyst available to be considered as an oxidation catalyst to reduce the carbon monoxide emissions under existing conditions at the cement plant. Thus further developments are inevitable.