The award is the only Nobel Prize revealed in Oslo, with the rest of the award announcements made in Stockholm each year.
But the competition is being closely watched in Sweden, home to the chemist Alfred Nobel who left a large share of his fortune in his will in 1895, in order to launch the prizes.
Snowden, the former intelligence analyst who revealed the extent of US global eavesdropping, has already won the 2014 Right Livelihood Award, which is described as Sweden's "alternative Nobel prize".
A hero to some and a traitor to others, he would be a highly controversial choice for the 8 million kronor prize ($1.1 million).
The Pakistani girls' education campaigner Malala Yousafzai – who was also a favourite last year – is also said to be in the running along with the pope and a Japanese pacifist group.
Predicting the winner is even harder than usual this year, as the Nobel committee has received a record 278 candidates, so experts only have the names of those made public by their sponsors to go on.
Other favourites, also tipped last year, were Congolese doctor Denis Mukwege who has treated female victims of sexual violence for the last 25 years, and the human rights activist Ales Bialiatski from Belarus, who was released from prison by the Russian-backed dictatorship in June.
The bookmakers Paddy Power are banking on Pope Francis for his outspoken defence of the poor, giving him 9/4 odds, far ahead of another candidate who is also believed to have been nominated — Vladimir Putin, a long shot at 50/1.
Previous Nobel Peace Prize winners include Mother Theresa, Nelson Mandela and Barack Obama. The award was given to the European Union in 2012.