The paper describes the basic studies, design, construction and operation of a shoreline OWC wave power pilot plant on the island of Pico, Azores, Portugal. Construction began in 1996. The concrete structure of the chamber (square planform with inside dimensions of 12m×12m at mean water level) was built in-situ on rocky bottom (about 8 m water depth), spanning a small natural harbour (gully). The plant was equipped with a horizontal-axis Wells turbine-generator set rated 400 kW. The plant was fully automated in order to supply electrical energy to the island grid on a permanent basis. It became operational in 1999. The paper describes the life of the plant during the following almost twenty years, including frequent repairs, modifications and the use of the plant as supplier of energy to the island grid, and as an infrastructure for research and training.