Curacao drinking water is produced from seawater, using reverse osmosis and evaporation technologies. The last drinking water plant is designed on a 7-stage treatment line including multimedia filtration, desalination on reverse osmosis, the second pass RO for TDS and boron removal, UV, remineralization through calcite filters, granular activated carbon and final chlorination before storage and distribution. The plant was commissioned at the end of 2005. The paper presents the first results of the plant optimization and the performance tests in terms of water quality, RO membrane performances based on the initial project and the site figure during the first months of operation. The Santa Barbara Desalination Plant delivers drinking water for half of the Curacao Island (east part), and is one of the first full-scale plants in operation applying 0.3 mg/L boron maximal concentration target.