He remains with the company until the end of December and hands over to Simon Oddie, who will now be interim chief executive as well as executive chairman.
The company highlighted that the decision reflects Europa’s strategy to diversify through new ventures in appraisal and development.
Europa said it continues its farm-out activities, though it had no new updates in that regard.
“Hugh was appointed CEO in 2011 and inherited a varied portfolio of exploration licences in Ireland, France, Western Sahara and Romania as well as onshore UK production,” Oddie said.
“He worked up and focused the company on a series of drillable exploration prospects capable of being farmed out. As a result, Europa has very high impact exploration positions offshore Atlantic margin in Ireland and Morocco as well as oil development and production onshore UK.”
Mackay, meanwhile, added: “I have enjoyed my eight years at Europa and am proud of the position we have built as a leading Atlantic margin explorer in Ireland and our new entry into Morocco.
“I am confident that the scene is now set for positive outcomes at Inishkea and Wressle and that the time is right for new leadership to take the company forward.”