A method for operating a gas turbine (11), which is used especially in a combined-cycle power plant (30), includes inducting and compressing air by the gas turbine (11), the compressed air is fed to a combustor (18, 19) for the combustion of a syngas which is produced from coal, and the hot gases which result during the combustion are expanded in a subsequent turbine (16, 17), performing work, wherein some of the compressed air is separated into oxygen and nitrogen, and the oxygen is used in a coal gasification plant (34) for producing the syngas. With such a method, a reduction of the NOx emission is achieved without noticeable loss of output and flexibility of operation by a gas turbine (11) with reheating being used, which includes two combustors (18, 19) and two turbines (16, 17), wherein in the first combustor (18) syngas is combusted, using the compressed air, and the resulting hot gases are expanded in the first turbine (16), and wherein in the second combustor syngas is combusted, using the gases which issue from the first turbine (16), and the resulting hot gases are expanded in the second turbine (17), the two combustors (18, 19) are operated with undiluted syngas, and the flame temperature (TF) in the first combustor (18) of the gas turbine (11) is lowered compared with the operation with natural gas (TNG), while the second combustor (19) is operated largely in the normal operation (TNG) which is designed for natural gas.