This paper addresses a systematic controller design for the TCSC device in power systems based on a Linear Matrix Inequality (LMI) pole placement technique. Requirements of performance can be expressed in terms of LMI's. In our formulation we combine a H ∞ controller design with some regional pole placement constraints using LMI's. The application of this controller, which is presented as an example in this paper, is effective in improving the damping ratio of a two-area four-machine test system. Furthermore, good damping ratio can be achieved and maintained over a larger range of operation with this LMI pole placement controller than with a conventionally designed H ∞ controller. Another benefit of this approach is that it results in a fixed parameter controller.