Key components of open-cycle ocean thermal energy conversion (OC-OTEC) systems—the flash evaporator, mist eliminator, passive predeaerator, two surface condenser stages, and mo direct-contact condenser stages—have been tested using seawater. These components operate at lower steam pressures and higher inlet noncondensable gas concentrations than do conventional power plant heat exchangers. The rate of heat exchanged between the evaporator and the condenser is on the order of 1.25 MW (thermal), requiring a warm seawater flow of about 0.1 m3/s; the cold seawater flow is on the order of half the warm water flow. In addition to characterizing the performance of the various components, the system has produced potable water from condensation of the steam produced in the evaporator. The information obtained in these tests is being used to design a larger-scale experiment in which net power production is expected to be demonstrated for the first time using OC-OTEC technology.