Barcelona's general director Antoni Rossich, director of football Raül Sanllehí and Brazilian representative André Cury have been negotiating the transfer of Douglas with Sao Paulo in Brazil on Tuesday.
Sao Paulo only own 60 percent of the player's rights - a company called Traffic own the remaining 40 percent - which makes it slightly more difficult to finalise than a normal transfer.
The meeting took place at the Estadio Morumbi in the city of Sao Paulo.
Barça expect to have everything sorted before next Monday, which is the deadline for registering new players in the Spanish league.
The Brazilian full-back will be immediately incorporated into Luis Enrique's squad - a loan move back to Sao Paulo is now out of the question as the Brazilian transfer market closed on August 15.
Douglas, 24, will sign a contract with Barça until 2019 and the cost of the transfer is expected to come in at around €6million.
Once the deal is confirmed, Enrique will be able to count on three players for the right side of his back four: Dani Alves, Martin Montoya and Douglas.