Congestion management is one of the most important issues for secure and reliable system operations in deregulated electricity market. This work presents an optimization approach for optimal allocation and optimal sizing of Thyristor Controlled Series Compensator (TCSC) or Unified Power Flow Controller (UPFC) in deregulated electricity market to reduce congestion. The proposed optimization technique has been used with an objective to minimize overall operating cost, maximize social welfare by placing TCSC or UPFC in a suitable location. In order to reduce the solution space two effective Indices (Marginal Congestion Index (MCI) and Active Power Spot Price Index (APSPI)) are employed for optimal placement of TCSC or UPFC. Once the location of TCSC or UPFC is identified, the optimal parameters of TCSC or UPFC are also determined. The proposed approach is carried out on modified IEEE 14-bus and IEEE 118-bus test systems and the results are presented to validate the approach.