This paper deals with the design of a solar thermal desalination system based on a multi-effect distillation (MED) plant connected to a double-effect absorption heat pump (DEAHP). To date, the only two demonstration projects employing this technology worldwide have been implemented at the PSA (Almeria, Spain). Two different prototypes of a DEAHP (LiBr-H2O), manufactured by the French company ENTROPIE, were connected to an existing multi-effect distillation unit (nominal PR 10.5) in 1991 and 2005, respectively. This paper presents the first experimentally validated design proposal for a solar desalination system based on MED-DEAHP technology. The overall performance ratio, experimentally measured at the Plataforma Solar de Almeria test facilities, was 20, which results in a 50% of reduction of the required solar field area compared to a solar MED system. (C) 2010 Elsevier B.V. All rights reserved.