Makai Ocean Engineering, Inc.’s Ocean Thermal Energy Conversion (OTEC) Heat Exchanger (HX) Testing program at the Ocean Energy Research Center (OERC) is focused on developing an economically viable OTEC power plant. Heat exchangers are one of the most expensive components in an OTEC power plant; proper heat exchanger selection is crucial to the economic viability of OTEC. Heat exchanger development must balance size, cost, and performance. To meet this goal, the OTEC HX Testing Program is divided into three areas: HX Performance Testing, HX Design Development, and Corrosion Testing. This report reviews Makai’s activities and summarizes the completion of the Milestones under APRISES11, conducted from March 2013 to December 2014.