Skysports.com understands West Ham and Fiorentina have come to an arrangement that will see Savio move back to Italy and Manuel da Costa head in the opposite direction to Upton Park.
The swap deal is only on a loan basis and will be until the end of the current campaign, when both parties will then reassess the situation.
Savio has struggled to establish himself since joining the Hammers in a big money move from Brescia in January.
West Ham boss Gianfranco Zola conceded earlier in the summer that the 19-year-old had failed to adapt to the physical demands and pace of English football but was hopeful he would do so given time.
However, it now looks likely he will return to Serie A for the rest of the current campaign as West Ham close on a deal for central defender Da Costa.
The talented Portugal Under 21 international is keen on a move to England and has previously attracted attention from Sunderland.
Da Costa spent the second half of last season on-loan at Sampdoria.
Fiorentina have been linked with West Ham defender Matthew Upson, but skysports.com has since learnt the England international is unlikely to leave East London for Italy.