United will play the Spanish giants in Washington on July 30 in the final game of a five-match tour which will see them play three Major League Soccer sides and an all-star match.
"Tours are a fantastic chance for the players to get away as a unit, to put in some good training sessions and to meet some of our fans around the world who don't have a chance to watch us play live every week," Manchester United manager Sir Alex Ferguson said.
"Our visits to the US are always enjoyable ones. The training facilities are excellent and we certainly found last year that, with the improving quality of the MLS teams, the games are very competitive, which is great preparation for a new season.
"To finish off with a match against Barcelona will be a special moment for all our fans in the States."
The Barcelona friendly will be a re-match of the 2009 Champions League final, when United were beaten in Rome by the La Liga outfit.
United's tour begins against New England Revolution on July 13 before a tripl to play the Seattle Sounders a week later. They then face Chicago Fire on July 23 before playing an MLS All-Stars team on July 27.
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