Shane Bauer and Josh Fattal are due in an Iranian court late Saturday evening Pacific Time for what Iranian authorities say will be the last hearing.
The hearing comes just before the start of the Islamic holiday of Ramadan, when Muslims traditionally pardon prisoners.
Bauer's fiance, Sara Shourd of Oakland, was detained along with the two men in 2009 but was released last year on $500,000 bail.
Sunday will mark the two year anniversary of the arrests, which came after the trio hiked along the Iran-Iraq border. The hikers have said they accidentally crossed into Iran, though Iranian officials say they have overwhelming evidence the three were American spies.