A former executive at the Dunkin’ Donuts fast-food chain is suing his ex-employer for $5 million, alleging the company has spoken so ill of him that he can’t find another job.

Michael O’Donovan, a former vice president of global research and development for Canton, Mass.-based Dunkin’ Brands Inc., alleges that a series of bad references and defamatory comments by Dunkin’ officials have damaged his reputation in the restaurant industry and killed numerous job prospects over the last two years. Since leaving Dunkin’ Brands in 2007 under confidential circumstances, he’s applied for jobs at Arby’s, Papa John’s, Wendy’s, Buca di Beppo, Buffets Inc. and the Back Bay Restaurant Group, but to no avail, according to court documents.