The paper presents the main features of transmission expansion problem (TEP). In accord with review the aims and influencing factors are defined. The competitive behaviors of market participants, transmission losses, discrete investment costs, various operating conditions are considered in the model. The model is a mixed-integer linear programming formulation for a static TEP in the competitive environment. The presented methodology is applied to six-node system. In order to point out efficiency of the model the results obtained are compared with traditional problem solution.