•Applying the gravitational search algorithm (GSA) to solve the combined heat and power economic dispatch (CHPED) problem.•Modeling the valve-point loading effect and transmission losses in the CHPED problem.•Verifying the effectiveness of the proposed method on different case studies.•Comparing the results of GSA-based CHPED problem with various heuristic algorithms such as GA, HS, EDHS, CPSO, and TVAC-PSO. This paper presents the application of a novel optimization algorithm, namely gravitational search algorithm (GSA) to solve the non-convex combined heat and power economic dispatch (CHPED) problems. The proposed approach is based on the gravitational law and the law of particles motion. The effectiveness of the suggested algorithm is tested on study-cases which include modeling of valve-point loading effect and transmission losses. Results of GSA-based CHPED problem in terms of quality solution and computational performance are compared with various algorithms to show the ability of the introduced algorithm in finding an operating point with lower fuel cost.