In this study, a 5 tons of refrigeration (60,000 BTU h-1) commercial absorption refrigeration unit was characterized and instrumented, and a simplified thermal and exergetic analysis of the system was performed, aiming the optimization of external operating parameters for maximum thermodynamic performance. The first and second law of thermodynamics were used to evaluate the energy (first law) and the exergy (second law) efficiencies of the system. The experimental results showed the existence of a double maximum for the thermal and exergetic efficiencies for the optimized unit with respect to the water mass flow rates of the cold and hot sides of the absorption refrigerator. Maximum variations of 30% and 44% in the first and second law efficiencies, respectively, were observed according to the mass flow rate range used, which stresses the importance of the optima found for maximum thermodynamic performance, and therefore minimum energy consumption in actual engineering applications.