NEW YORK (Reuters) - Billionaire investor William Ackman said there is room for Air Products and Chemicals Inc's (>> Air Products & Chemicals, Inc.) stock price to double in the next few years if the industrial gas producer hires the right chief executive.

"This is a $200 plus stock over the next three years with new management," Ackman said at an investment conference. Ackman's Pershing Square Capital Management is Air Products' biggest shareholder with a 9.71 percent stake.

The company has been looking for a new leader since Chief Executive Officer John McGlade said in September that he would retire this year. McGlade plans to stay on as chairman of the board for a limited time as the new CEO settles in.

Air Products is one of the world's largest industrial gas companies, breaking down air to form oxygen, nitrogen and other components used in construction, healthcare, oil refining and scores of other industries.

McGlade's replacement will have to turn around a corporate culture that has long had a reputation as top-down and bureaucratic. That inefficiency has cost the company market share and dented margins, which badly trail Praxair Inc (>> Praxair, Inc.) and other rivals.

Air Products also has invested capital in unrelated businesses, including specialty chemicals for electronics makers and liquefied natural gas heat exchangers, that Ackman and others have said diverts the company from its core mission.

Since McGlade's announcement, the company's stock price has moved up and down and is now trading only about 2 percent higher at $112.04 then where it was in late September.

As an activist investor, Ackman knows firsthand how selecting the right person for the top job can make or break investments.

Watching Ron Johnson's vision for remaking J.C.Penney (>> J.C. Penney Company, Inc.) fall apart cost his hedge fund $500 million, but installing Hunter Harrison at Canadian Pacific (>> Canadian Pacific Railway Limited) helped him earn more than $2 billion in less than two years.

"The risk at Air Products is whether or not they are going to choose the right CEO," Ackman said at the 2014 Harbor Investment Conference, which he runs with Mark Axelowitz.

Pershing Square does not sit on the Air Products board and will have no official say in who ends up getting the job, Ackman said.

But as the biggest shareholder, the hedge fund does have significant influence over the decision.

"No one would be willing to take the job without having the biggest shareholder on their side," Ackman said.

(Editing by Jonathan Oatis)

By Svea Herbst-Bayliss and Ernest Scheyder