In this work, a numerical model to quantify the enhancement of the performance of a lithium bromide absorption chiller by means of alcoholic additives is presented. The model is constituted with mass and energy balances, and is validated with experimental data of a single-stage absorption chiller with a nominal cooling capacity of 5 kW. During the simulation, inlet temperature of the hot water flowing into the generator is varied according to experimental data of a solar collector facility installed in Kassel (Germany) with an aperture area of 150 m(2). The temperature of the cooling water entering the absorber is varied as well. Results show that COP and cooling capacity of the absorption chiller are enhanced up to 83% when small quantities of surfactants are added into the aqueous lithium bromide solution.