This communication presents a finite time thermodynamic optimization of a simple vapour absorption refrigeration system affected by both external and internal irreversibility. External heat reservoirs (heat source/sink) have been considered of finite heat capacity. For a given input heat transfer rate in the generator, the cooling load has been maximized. The optimal bounds for the coefficient of performance (COP) and working fluid temperatures of the absorption system are determined at the maximum cooling capacity. The parametric study gives the variation of the maximum cooling capacity, the COP, working fluid temperatures and heat transfer rate between the system and its thermal reservoirs with operating variables (viz. inlet temperature of heat reservoirs, finite thermal capacitance of external fluid, effectiveness of the heat exchangers and internal irreversibility parameter).