The aim of the invention is to increase the efficiency of a gas turbine system. Said aim is achieved by transferring at least one portion of the heat of the waste gases of a gas turbine to a working medium of a thermodynamic circulation process, which comprises at least two substances featuring non-isothermal evaporation and condensation. Said circulation process allows the residual heat of the waste gases to be used for additionally generating electrical or mechanical power, especially at waste gas temperatures ranging from 100 to 200° C. Even previously existing systems can be retrofitted in a simple manner with such a circulation process.