Climate change present a great threat to islands due to their remoteness. Furthermore, these isolated energy systems still heavily depend on imported electricity from the mainland. Therefore, various initiatives serve to encourage island communities, municipalities and the local population to use renewable energy and new integrated solutions for the management of the islands´ natural resources. Both the cities Cres and Mali Lošinj and the representatives of the Cres-Lošinj archipelago have signed the Political Declaration on Clean Energy for EU Islands, committing to promote sustainable development and to lead the decarbonisation of the islands´ power sector. The main aim of this paper is to illustrate the potential of the ocean thermal energy and nit's a possible application for the installation of saltwater heating pumps in public buildings of the Cres-Lošinj Archipelago. In the first part of the paper, the thermodynamic laws behind the heat pumps, their operating principle and design are being discussed. Seawater as a heat source-sink and the intake of seawater are being outlined in this part of the paper. Heat pumps that are already being used on the Adriatic coast are also explored. In the second part of the paper, the facilities suitable for the installation of heat pumps in the Cres-Lošinj archipelago are discussed. Calculations of thermal load and annual heating energy demand were made according to the standards HRN EN 12831:2003 and HRN EN ISO 13790. Calculations of cooling load for the selected buildings was simplified for the reasons stated in part of the paper related to refrigeration. Last but not least, a techno-economic analysis of the heat pumps installation was carried out. Additionally, a comparison was drawn between the current situation and possible scenarios of heat pump installation that include saving energy and reduced CO2 emissions.