In a method for utilizing alternative fuels in the production of clinker or cement the alternative fuels are employed in reactors (4) for the preheating and/or precalcining of raw meal in a combustion device (17) separate from the burners (12) of the respective reactor (4) and are at least partially burnt whereupon an, if necessary, complete combustion is carried out inside the reactors (4) with the combustion oxygen fed to the burner (12) of the reactor (4) in excess of stoichiometry. The device for utilizing alternative fuels in the production of clinker or cement having a clinker kiln (1) and a reactor (4) with burners (12) for preheating and calcining of raw meal and having at least one duct (18) for combustion air or -oxygen respectively is characterized in that a separate combustion device (17) having a conveyor for alternative fuels such as, for instance, a pusher or a screw conveyor (16) is provided and opens inside the respective reactor (4).