An environmental impact assessment (EIA) was made for the operation of a 1MWe open-cycle OTEC plant on Cozumel Island, Quintana Roo. Due to its bathymetric characteristics and its proximity to the population center, the ideal location for the placement of the OTEC plant is in the western coastal area of the island. An environmental inventory was developed in which the susceptible factors to be impacted were described (air, soil, water, landscape, geology and flora). The essential components of the OC-OTEC PLANT operation process were studied: vacuum pump, flash evaporator, turbine, condenser and pipes. An impact matrix (Leopold matrix) was created, which prompts to impacts on the environment list, generated by the OC-OTEC PLANT operation: CO2 emissions; nutrients dragged to the surface; artificial reef effect/contamination by heavy metal salts; drag and compression of organisms; redistribution of oceanic water bodies; impacts by organic antifouling chemicals; noise; illumination; turtle nesting alteration; brine discharges; cause significant public controversy; alteration and interruption of migration routes; and waste, among others. Once the most significant impacts were assessed through the Leopold matrix, corrective and preventive measures were established on those actions, in order to minimize their negative impact on the environment.