This paper proposes a new method of optimal number and location of TCSC using mixed integer non-linear programming approach in the deregulated electricity markets. Optimal number and location of TCSC controller can effectively enhance system loadability and their placement is a crucial issue due to their high cost. Since, in the competitive electricity environment more and more transactions are negotiated, which can compromise the system security. Therefore, it has become essential to determine secure transactions occurring in the new environment for better planning and management. The system loadability has been determined in a hybrid market model utilizing the secure transaction matrix. The proposed technique has been tested on IEEE 24-bus reliability test system (RTS).