Donald, who is currently appearing in the Channel 4 lawyer drama Dirty Sexy Money, said Kiefer Sutherland had a tough time in prison but it helped him to focus on how to improve the explosive drama.
"Jail was tough for him. He had 48 days inside, 23 hours a day in solitary. It was very, very cold," he told Newsbeat.
"There were no windows. He had no community. I also made a deposit at the prison so he could call out. We were given 14 minutes for every call.
"When he would call, you weren't prepared and when I got to speak to him I didn't get to say everything I wanted to. I wrote to him every other day though.
"But now that he's out, he said that the next two seasons of 24 will be the best two years of television in the United States."
Previous offence
Kiefer Sutherland was arrested and found to be over the legal alcohol limit after leaving a party last year. He was still on probation for a previous offence and he served a 48-day sentence for drink driving.
Donald also revealed how he turned down the chance to appear on 24 as Jack Bauer's father.
"We had a long dinner and he asked me to play his dad in 24," he explained.
"Jail was tough for Kiefer - he had 48 days inside, 23 hours a day in solitary, it was very, very cold"
"He said, 'I'll go back and see what the writers have in mind'. He came back and said, 'No dad, they want you to try and kill me'. I said, 'No way, that's not going to work'. So they hired James Cromwell instead."
The actor did say that he tried persuade the writers to bring him in during a later season though.
He added: "I said, 'Maybe you could have me at the very end, rescuing you from some place and I could look at you and you could look at me and I say 'He (Phillip Bauer) was your mother's husband but I'm your biological dad'. But I don't think they'll ever do that."
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