In the above paper a hybrid seeker optimization algorithm and sequential quadratic programming (SOA-SQP) is proposed for solving the dynamic economic dispatch (DED) problem. The DED problem is formulated with the objective to minimize the total cost function over a dispatch period and satisfying the ramp rate constraints and other constraints. According to the optimal results for the two test systems, none of the results satisfy the ramp rate constraints. It seems that the ramp rate constraints are not considered and the solutions due to violation of constraints are not feasible. (C) 2012 Elsevier Ltd. All rights reserved.