Speaking from London, Pat Kember appealed to her husband's captors to free him and his friends.
"Norman keenly takes care of others," she said.
"He believes that all people should live peacefully. He courageously resists all forms of aggression. He went to Iraq to help Iraqis, stop the widespread violations, identify with the circumstances in which they live and make Iraq a more peaceful place.
"I beg you to release Norman and his colleagues so they could continue their work for peace in Iraq. They are friends and allies of Iraqis who want to help you overcome evil by performing good deeds".
Norman Kember was taken with James Loney and Harmeet Singh Sooden, both Canadians, and Tom Fox, an American, on 26 November in Baghdad.
Kember, an anti-war campaigner aged 74, was in Iraq investigating human rights abuses.
In a message broadcast by Aljazeera on Friday, their captors threatened to kill them by 8 December unless all Iraqi detainees were released.