hydrothermal scheduling is one of the most important tasks to be performed in the operational planning of power systems. The practical hydrothermal system is a highly complex and it possesses a nonlinear relationship with the problem variables. In this work a new optimization technique based on biogeography presents for solving hydrothermal scheduling problem. Biogeography Based Optimization approach (BBO) is applied on a multi-reservoir cascaded hydrothermal-electric system with nonlinear generation of water discharge rate and storage volume. Results obtained from this method are compared with other reported methods are Particle Swarm Optimization (PSO), Evolutionary Programming (EP) and Simulated Annealing (SA). It is shown that BBO approach appears to be the best in terms of minimum cost and execution time.