This paper presents the use of an enhanced version of conventional cuckoo search algorithm (ECSA) for solving optimal generation coordination of hydrothermal system where the objective is to minimize both fuel cost and emission, and the hydro model is represented as a quadratic function of water discharge with respect to generation. The ECSA method is built for the optimal operation based on several modifications on conventional Cuckoo search algorithm (CSA). In the ECSA method, by evaluating the fitness of all initial eggs they are divided into two parts including the high quality one with lower fitness value and bad quality one with higher fitness value. The ECSA is tested on several systems and obtained results from the ECSA are compared those from other methods. The comparison reveals that the ECSA is so efficient for the considered problem.