Transmission expansion planning (TEP) refers to specifying the place, time, and number of new transmission lines that should be established, so that given the network available, one can fulfill the potential demand of the power system in the future in terms of both operation and economic aspects (given the system constraints). Nevertheless, TEP is intrinsically a large-scale, mixed integer, nonlinear, and non-convex problem, which basically has several local optima. Solving this problem is very difficult and its computation is very time-consuming. To solve such a problem, a powerful optimization method is needed. In this paper, to solve the TEP problem, a new optimization algorithm called bacterial foraging optimization algorithm (BFOA) has been used. The proposed method has been studied on a 6-bus network for different scenarios, with the results indicating efficiency of BFOA. Manuscript profile