Abstract: High efficiency heat pump combining absorption and solution concentration change. The method gives a few times higher efficiency for heat transfer applications like heating—air conditioning. It is a heat and mechanical compression method using liquid electrolyte solutions, combining steam absorption, solution concentration change and mechanical compression. There is no heat consumption. Steam condensation is performed by a high concentration solution and vaporization from a low concentration solution reducing in this way the required mechanical compression of the known refrigeration cycle. The method may be used for work production too, exploiting moderate temperature heat sources.