New simple and accurate correlations of the equilibrium properties and solution enthalpies for NH3/H2O/alkaline hydroxide mixtures are presented for use in the modeling and design of absorption chillers in a temperature range between 273.15 and 353.15 K The correlations are used to calculate the P-T-x diagrams and show the effect of hydroxide on the liquid-vapor equilibrium. Finally, the correlations presented are used to estimate the improvement in the cycle performance in absorption chillers when NH3/H2O mixtures containing NaOH are used instead of the conventional NH3/H2O mixture. Results show that the addition of hydroxide can significantly decrease the generator temperature of ammonia/water absorption refrigeration cycles while simultaneously increasing the Coefficient of Performance (COP). For a NaOH concentration of 12%, the temperature at the generator decreases by about 17 degrees C, the COP increases by 28%, and the size of the rectifier can be up to 46% less than that required when the conventional NH3/H2O cycle is used.