A polynomial model is developed to predict the coefficient of performance of a water purification process integrated to an absorption heat transformer. The range of the coefficient of performance operations was from 0.21 to 0.39. This model used: inlet temperature in the generator which comes from the absorber, outlet temperature in the absorber that comes from the generator, inlet temperature in the absorber that comes from the generator, water-lithium bromide solution inlet concentration in the generator that comes from the absorber and the pressure in the absorber and generator. A polynomial model is presented in order to obtain coefficient of performance prediction with a determination coefficient of 0.9919. Level surfaces of the coefficient of performance against the inlet variables for the polynomial model and residual analysis were presented with the aim of validating the model. This work has the purpose of providing faster and simpler solutions instead of the complex equations used for the analysis of the heat transformer in order to obtain accurate coefficient of performance prediction. The operation variable with the greater contribution of determination coefficient is presented.