Barcelona said in a statement they had been in negotiations with Ronaldinho's brother and agent Roberto Assis on Saturday morning.
"Club president Joan Laporta, vice-presidents Sandro Rosell and Ferran Soriano and managing director Javier Perez Farguell are agreeing with the player's representative the final details of the deal," the statement said.
Spanish media reports said Ronaldinho was due to arrive in Spain later on Saturday to close the deal.
Barcelona have been battling with Manchester United for the signature of Ronaldinho, who was one of the most influential figures in Brazil's World Cup triumph last year.
