Trillo Nuclear Power Plant is a nuclear power station in Spain. The Trillo nuclear power plant is located in the municipal area of the same name in the province of Guadalajara, on the banks of the river Tajo, and has a nuclear steam supply system made up of a three-loop pressurised light water reactor (PWR) with an authorised thermal output of 3,010 MWt and an electrical power of 1,066 MWe. Ownership of the plant is shared between the companies Iberdrola (48%), Unión Fenosa (34.5%), Hidroeléctrica del Cantábrico (15.5%) and Nuclenor (2%). The Trillo I nuclear power plant belongs to the third generation of Spanish plants and began its commercial operation on August 22nd 1988.

It consists of one pressurized water reactor (PWR) of 1066 MWe. Construction of unit one began in 1979, and first criticality was on 14 May 1988.

A planned second identical unit was cancelled soon after construction began following a change of government in 1983.