Andrew Mill was previously managing director of the Orkney facility, which provides grid-connected open sea testing for wave and tidal energy devices, between 2003 and 2005. Now chief executive at the National Renewable Energy Centre in Blyth, Northumberland, Mr Mill is becoming chairman designate at EMEC from next month.
He will replace Bill Edgar, who has been in the role since 2005, when he steps down later this year.
Also joining the EMEC board as a non-executive director is Ron Chapman, who replaces Hugh MacNab.
Mr Chapman held senior roles in ScottishPower and the National Grid Group.
He is also chairman at the Water Research Centre in Wiltshire.