Ahstract- Thyristor-controlled series capacitor (TCSC) devices have been utilized for enhancing transmission network loadability. The technical benefit of the TCSC devices comes at the expense of their high investment cost. In this paper, a new approach is proposed to provide a profound insight into the compromises between technical and economical aspects of installing TCSC devices in a transmission network. The proposed approach is a multiobjective optimization based algorithm used to maximize the loadability of the network and to minimize the investment cost of installing TCSCs under secured operation conditions. The results provide an efficient set of nondominated solutions to maximize the loadability at minimal cost for the decision-making process. The IEEE lIS-bus system is used as a test case to validate the effectiveness of the proposed method. Furthermore, the results are analyzed and compared with available results in the literature.