This paper proposes a method to minimize the real power loss (RPL) of a power system transmission network using a new meta-heuristic algorithm known as firefly algorithm (FA) by optimizing the control variables such as transformer taps, UPFC location and UPFC series injected voltage magnitude and phase angle. A software program is developed in MATLAB environment for FA to minimize the RPL by optimizing (i) only the transformer tap values, (ii) only UPFC location and its variables with optimized tap values and (iii) UPFC location and its variables along with transformer tap setting values simultaneously. Interior point successive linear programming (IPSLP) technique and real coded genetic algorithm (RCGA) are considered here to compare the results and to show the efficiency and superiority of the proposed FA towards the optimization of RPL. Also in this paper, bacteria foraging algorithm (BFA) is adopted to validate the results of the proposed algorithm.