In a double-effect series flow vapour absorption refrigeration system (VARS), an optimum value of the low-pressure generator temperature exists at which all the vapour generated at the high-pressure generator is condensed. At these conditions, a comparative study of the performance of VARS using environment friendly refrigerants such as, R32, R134a, and R124 with N,N'-dimethyl acetamide (DMAC) as the absorbent is made. It is found that the system with R32-DMAC gives the best performance at high evaporator temperatures. R124-DMAC may be preferred at extreme operating conditions like low evaporator and high heat rejection temperatures. Influence of operating temperatures (high-pressure generator, evaporator, condenser and absorber) and the effectiveness of heat exchangers on the optimum low-pressure generator temperature, cut-off temperature, circulation ratio and coefficient of performance are studied.