"Barcelona and the player Rafa Marquez have agreed to rescind, by mutual consent, the contract that tied the two parties together until June 30, 2012," Barca said on their website on Saturday.
If the deal with the Red Bulls goes through, Marquez would join former Barca team-mate Thierry Henry, the French striker who this month moved to Major League Soccer (MLS) after he was also freed from his contract.
Marquez, 31, can operate as a centre back or defensive midfielder and would be the Red Bulls' third "designated player", whose wages are mostly exempt from the salary cap, along with Henry and Colombian Juan Pablo Angel.
He joined Barca from French side Monaco in 2003 and has won four Spanish league titles and two European Champions League crowns.