A court in Bratislava court has ruled that Enel’s contract to operate the plant was invalid.
The Slovak Government and Enel have been at dispute over the maintenance and costs of the facility.
Enel’s subsidiary Slovenske Elektrarne owns a 66% stake in the hydropower plant while the government owns the remaining.
The government will now take over Enel’s stake and the operations of the plant.
Slovakia Prime Minister Robert Fico was quoted by the Wall Street Journal as saying: "We will strongly seek…that Enel returns all money which it earned operating the hydropower plant for eight years on the basis of an invalid contract."
The government estimates that up to €40m has been generated annually by the Gabcikovo plant in eight years.
Enel spokeswoman said: "(Enel) will appeal the decision once it receives official delivery of the court’s decision and its reasoning.
"The company remains convinced of the validity of the contract as also confirmed by the first instance decision of court on November 19th, 2013."
