This study deals with thermodynamic and economic analysis of a combined gas turbine and Organic Rankine Cycle integrated with a biomass gasifier. A modified model is used to increase the precision of the gasifier thermodynamic model. Seven decision variables, namely, biomass gasification temperature (T_gasif), combustion temperature (T_comb), gas turbine inlet temperature (T₃), gas turbine isentropic efficiency (η_GT), compressor isentropic efficiency (η_comp), compressor pressure ration (r_p) and maximum ORC operating pressure (P_3R), are selected as the main decision variables of the combined system. The total cost rate and exergy efficiency of the system are chosen as the two main objective functions. A group method of data handling (GMDH) type neural network and evolutionary algorithm (EAs) are used for modeling the effects of the seven decision variables on both objective functions. The result of …