In this paper, a Linear Quadratic Regulator (LQR) based PI controller is proposed for the Integrator plus Time Delay Process (IPTD). In LQR PI controller design process the selection of weight matrices ‘Q’ plays a key role in order to minimize settling time, peak overshoot and Integral Errors. So, In order to improve the system performance, a new feedback gain matrix is proposed for the optimal selection of weight matrices in the controller design. First, the LQR PI controller is designed for First order Time Delay Process (FOPDT) and then grabbed the formulas for IPTD process by assuming the state variable as zero. The simulation results are presented to validate the proposed method by using different IPTD process. The proposed controller is also experimentally validated on a temperature control process. © 2017, Gazi University Eti Mahallesi. All rights reserved.