The José María de Oriol-Alcántara II reservoir, better known as the Alcántara reservoir, is an artificial reservoir located in the province of Cáceres, in the Autonomous Community of Extremadura, Spain and located on the Tajo riverbed.
It is commonly cited as Alcántara Reservoir or Alcántara Reservoir, but there is another supply dam in the same municipality that receives the name of Presa de Alcántara I.
It regulates a large part of the Tajo river, the longest in the Iberian Peninsula. Downstream from the José Mª de Oriol dam and before entering Portugal are the dam and the Cedillo dam. At the time of its construction it was the second largest reserve in Europe.
The famous Alcántara bridge, from Roman times, is only 600 meters downstream from the dam. The island of Cabeza Gorda is inside the reservoir.