Ocean thermal energy conversion (OTEC ) utilizes the thermal gradient available in the ocean to operate a heat engine to produce work output. Even though the concept is simple and old for almost one century, during last three decades, it has gained momentum due to worldwide search for a clean, continuous energy source to replace the fossil fuels. There are technological hurdles to overcome to tap the immense potential of OTEC. But still the technology is mature enough to establish commercial power plants. This chapter presents the technological and economical aspects of the OTEC with an overview of the current status. It also suggests some further research and technological guidance based on the Indian OTEC experiences for this promising technology for future.