In the present paper, the additives 1-octanol and 2-ethyl-1-hexanol, have been used for the first time in a 2 kW single-stage heat transformer installed in the Energy Research Centre of the National University of Mexico utilizing H2O/LiBr, operating at absorber temperatures in a range between 70 and 110degreesC. The results showed that at the same conditions, absorber temperatures increased about 5degreesC by adding 400 ppm of 2-ethyl-1-hexanol to the lithium bromide mixture. Also it was shown that the coefficient of performance increases up to 40% with the same additive. Copyright (C) 2005 John Wiley Sons, Ltd.