In this research paper, energy and exergy analyses of water lithium bromide half effect vapour absorption refrigeration system has been carried out. Based on energy and exergy analysis the optimum intermediate pressure is computed corresponding to maximum values of coefficient of performance and exergetic efficiency under various operating conditions. It is found that the optimum intermediate pressure corresponding to maximum values of coefficient of performance and exergetic efficiency is same. The effects of low and high pressure generator temperatures, evaporator temperature, effectiveness of solution heat exchangers and difference between low and high pressure generator temperatures have been considered in computing optimum intermediate pressure. The maximum COP varies between 0.415 - 0.438 and maximum exergetic efficiency varies between 6.96-13.74%.