Time Warner Inc has named Google executive Tim Armstrong to lead AOL, in what was seen as a bold move to reverse the fortunes of the struggling Internet unit in preparation for a spin-off.

The hire was a welcome surprise to Wall Street analysts, who see Armstrong as a respected executive who had overseen Google's Americas operations. He is best known for his work in developing Google's online advertising business and was widely touted last year as a CEO candidate for Yahoo Inc.

"Tim is the right executive to move AOL into the next phase of its evolution," Time Warner Chief Executive Jeff Bewkes said in a statement announcing Armstrong's appointment as AOL chairman and chief executive.

"He'll also be helpful in helping Time Warner determine the optimal structure for AOL."

Armstrong replaces Randy Falco, an ex-NBC executive, who will leave the company after a transition period, as will AOL Chief Operating Officer Ron Grant, Time Warner said. Falco and Grant were appointed in November 2006.

Bewkes has publicly said he is looking for the best way to resolve the future of AOL at Time Warner, including either a spin-off or merger with a partner such as Yahoo or Microsoft Corp's MSN.

Time Warner has held on-off talks with Yahoo in particular about Yahoo combining with AOL's audience and advertising business.