In this study, the thermal economic generation (dispatch) is solved using MATLAB optimization tools. First, the thermal economic dispatch problem is reviewed, concentrating on the -iteration method to solve the problem. The MATLAB optimization function fmincon is looked into describing its parameters and outputs. Utilization of fmincon to solve the thermal economic dispatch problem is detailed. The practical implementation includes IEEE published data system consisting of 26 units, with all the units committed. The second system consists of 10 units with a possibility of decommitting some of them. The results have proved the effectiveness of the MATLAB optimization tools to solve large-scale power systems problems..................... Keywords:............ Thermal Economic Dispatch, Optimal Generation, Lambda Iteration Method, MATLAB Optimization Functions.