"Andy Geiger is one of the most respected and admired leaders in college athletics, and he has had a tremendous impact at Ohio State," Tressel said.
"Andy cares deeply about his coaches, his staff and all of our student-athletes. That is one of the things that makes him such a special person.
"We as a football family owe a great deal to his guidance, wisdom and leadership.
"From a personal standpoint, I very much appreciate the four-plus years I that I have spent with him. Ellen and I look forward to continuing our relationship with he and Eleanor in the future."
OSU men's basketball coach Thad Matta also addressed Geiger's retirement following his team's loss at Illinois Wednesday night.
"I couldn't be happier for him," Matta said. "He is one of the greatest men I have ever met in my life. He and his wife Eleanor ... he told me he would not be here long. He said, `I'm going to be up front with you.'
"He said he was going to take Eleanor on the longest date of her life. He is a guy who deserves a great retirement.
"I am thankful he gave me this opportunity at Ohio State."
Earlier in the day, WBNS-AM personalities (and former OSU football players) Kirk Herbstreit and Chris Spielman discussed Geiger's departure.
"You knew that this might happen and it was a possibility," Herbstreit said by phone from his ESPN duties in Miami. "It isn't a big shock and not a big surprise. It is the unfortunate culmination of a lot of events that have forced Andy into early retirement."
Spielman said Geiger's comments in an article in The New York Times earlier this week made it clear he would not be around for the long haul.
"He admitted he was not passionate (about the job) any more," Spielman said. "That takes a lot of guts to say, `I'm done.' I give him credit for being honest with himself."
Herbstreit mentioned Oklahoma's Joe Castiglione and Florida's Jeremy Foley as possible successors from outside the university.
"It's a very unique place," Herbstreit said of OSU. "There should be a lot of people interested in that job."
(EDITOR'S NOTE -- We will share reaction from men's basketball coach Thad Matta after tonight's game at Illinois.)