Lord Blyth of Rowington to step down after eight years in the role
Dr Franz Humer will succeed Rowington from July 2008.
The group's board said Humer, currently a non-executive director of Diageo, would take up his appointment after retiring from his current role as chief executive of F. Hoffmann-La-Roche.
Blyth said: "Franz has a first class track record with considerable experience of international business in both mature and developing markets.
"During this time as a non executive director he has demonstrated to the whole board the qualities that will allow him to be a very successful chairman of Diageo."
Humer said he was "delighted and honoured" to be offered the appointment.