Electrical power system is very complex and it requires very careful design of new equipmentâ€™srnwhich are needed to improve electric power utilization, enhancing power system stability, powerrnloss minimization and power transfer capability. The existing power transmission network ofrnEthiopia consists of 45kV, 66kV, 132kV, 230kV and 400kV lines. This thesis mainly focused onrn132kV transmission line of Eastern region of Ethiopia. rn Transmission Line loss minimization and voltage profile improvement in the transmission linernare challenging problems. This thesis analyze the impact of using unified power flow controllerrn(UPFC) in the transmission line. The UPFC is the most versatile and complex power electronicsrnequipmentâ€™s that has emerged for control and optimization of power flow in electric powerrntransmission systems. It is a combination of series and parallel compensation and can thereforernprovide active and reactive control to achieve maximum power transfer, system stability, andrnvoltage profile improvement and minimize transmission line loss. rnUnified Power Flow Controller is designed for the transmission line to increase power transferrncapability, reduce power loss and improve voltage profile. The UPFC has been simulated usingrnDIgSILENT Power Factory Software. The simulation results showed that all the bus voltages arernwithin acceptable limit which is above 0.95p.u. After incorporating the UPFC the total activernpower loss is reduced from 4.295MW to 1.908, from 2.387MW to 1.306MW and from 1.166MWrnto 0.454MW for peak load condition, average load condition and minimum load conditionrnrespectively. The total reactive power loss is reduced from 9.2MVAr to 3.3MVAr, from 6.1MVArrnto 2MVAr and from 4.6MVAr to 0.9MVAr for peak load condition, average load condition andrnminimum load condition respectively. rnTherefore, by incorporating the designed Unified Power Flow Controller voltage profiles in thernEastern Region of Ethiopia is improved and transmission line loss is minimized.