Freddie Prinze Jr and Kiefer Sutherland in 24
Speaking on Saturday at the 2014 San Diego Comic-Con as he promoted the new Disney series Star Wars Rebels, Freddie called the show "terrible" and claimed Kiefer was "unprofessional".
He added: "I hated every moment of it."
The American channel Fox who made the worldwide smash TV show also responded, adding: "It's so out of left field, 5 years later. We wouldn't have done another 24 if Kiefer was anything like Freddie described."
Freddie joined the cast of 24 in 2009, and became a lead character for one season.
Freddie Prinze Jr in 2009
He added: "I just wanted to quit the business after that. So, I just sort of stopped. I went and worked for Vince McMahon at the WWE for Christ's sake and it was a crazier job than working with Kiefer."
Freddie also spoke unfavourably about his height comparison with Kiefer, admitting: "[MacMahon] was cool and tall. I didn't have to take my shoes off to do scenes with him, which they made me do. Just put the guy on an apple box or don't hire me next time. You know I'm 6 feet..."
Freddie found fame in the 1990s in films such as I Know What You Did Last Summer and She's All That, and is married to Buffy The Vampire Slayer actress Sarah Michelle Gellar.
It's a little princess!