Maintenance scheduling of power generators is of particular importance for power grids from both economic and reliability aspects. In this paper, the discrete firefly algorithm is implemented for maintenance scheduling of generators. This project utilizes the combination of the discrete firefly algorithm, as the main tool, and heuristic methods, as the secondary tool, for constructing initial solutions and searching the solution space. The paper investigates a case study consisting of a 32-generator problem formulated as a mixed-integer problem. The performance of the proposed method is compared with those in the literature and its strengths and weaknesses are discussed. The obtained results showed that performance of the proposed algorithm is not highly affected by its parameters’ values and is capable of providing multiple efficient maintenance schedules in a desirable time.