In hot and humid regions, due to the limitation of peak power, it is vital to reduce the electrical power consumption of multi-chiller systems since their consumption noticeably increases if the chillers are improperly managed. For this aim, optimal chiller loading (OCL) is one of the most important issues in such systems. The ultimate aim of the OCL problem is to determine the partial load ratio (PLR) of each chiller with respect to the cooling load demand. Owing to the nonlinearity of the OCL problem, a powerful search method should be employed to efficiently solve this problem. In this paper, general algebraic modeling system (GAMS) has been proposed to solve OCL problem. GAMS is an efficient and easy to implement high level computer programming language for modeling and solving optimization problems (linear, nonlinear and mixed integer). In order to evaluate the efficiency of the proposed methodology, two case studies are solved and the results are compared with the results obtained by both conventional and heuristic search methods. The results represent that GAMS produces promising results in comparison with the other methods. (C) 2015 Elsevier Ltd. All rights reserved.