Rafinha will join Celta Vigo in a season-long loan, with the midfielder set to travel to Galicia to sign a contract and an announcement expected imminently.
The Brazilian international, who has featured in all three of Barcelona's games so far this season, has agreed a new contract with the Catalan club as his current agreement ends next summer.
Rafinha spent a successful season on loan at Celta in 2013-14 under Luis Enrique. but has seen opportunities harder to come by at Barca and has had his progress interrupted by injuries.
He was also wanted by Valencia coach Marcelino, but club owner Peter Lim vetoed a deal earlier this summer.
Meanwhile, Ivan Rakitic is the subject of late interest from Italian side Juventus.
Barca had hoped to use the Croatian in a makeweight for a deal to sign Neymar from PSG, but Rakitic was not open to moving to Paris.
Barca have too many midfielders in their squad, and would be willing to Rakitic as well as losing Rafinha if the right offers come in.
The transfer window closes at 7pm BST in Italy.
