A combined cycle power plant (10) has a gas turbine (11), a heat recovery steam generator (16) which is connected downstream to the gas turbine (11) and delivers steam to a steam turbine (19), an exhaust gas recycling line (28) which returns some of the exhaust gases, which flow from the exhaust of the gas turbine (11) through the heat recovery steam generator (16), to the inlet of the gas turbine (11), and also a CO2 separating plant (25) which separates from the non-returned part of the exhaust gases the CO2 which is contained therein and delivers it to a CO2 outlet. A reduction of the equipment cost or a flexible adaptation of the operation can be achieved by a supplementary firing (17) being associated with the heat recovery steam generator (16), which by combusting a carbonaceous fuel produces additional exhaust gases with CO2 content and transmits them through the heat recovery steam generator (16).