The cuckoo search (CS) algorithm is a simple and effective global optimization algorithm. It has been successfully applied to solve a wide range of real- world optimization problem. In this paper, a modified CS algorithm is applied to determine the feasible optimal solution of the economic load dispatch problem considering various generator constraints. In order to solve the problem of being trapped into the local optima, a new mutation scheme, inspired by the DE/current-to-gr_best/1, is incorporated in standard CS to enrich the searching behavior and solution quality and to avoid being trapped into local optimum. In order to verify the performance of our approach, the proposed approach is tested with two power system cases consisting of 3, 6, 15, and 40 thermal units with generator constraints. State-of-the-art optimization techniques are compared with simulation results obtaining proposed method to illustrate the efficiency of the proposed method and to show that the improved CS could be used as a reliable tool for solving economic load dispatch problems with generator constraints. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]