(CNN) -- Chinese authorities have released activist Hu Jia, his wife posted Sunday on Twitter.
"On a sleepless night at 2:30, Hu Jia arrived at home. Safe, very happy. Needs to rest for a while. Thanks to each of you," Zeng Jinyan wrote in the tweet.
Zeng is married to Hu Jia, a human rights activist who served a three-and-a-half-year sentence for "incitement to subvert state power," according to the New York-based Human Rights Watch.
Hu had written a series of stories denouncing the human rights situation in China ahead of the 2008 Olympic Games in Beijing, the group said. He also has been active on AIDS issues in China.
Another prominent activist, Ai Weiwei, was released on bail Wednesday -- apparently with conditions -- after he spent nearly three months in prison on charges of tax evasion, according to the state-run Xinhua news agency.
Ai is an outspoken critic of Chinese policies and is renowned as a conceptual artist, particularly for designing the Bird's Nest stadium for the 2008 Beijing Olympics -- against which Ai later urged a boycott because he said China was using it as propaganda.