The Serie A club have been negotiating with Chelsea to keep hold of the Egypt international, who has also been linked with??Inter Milan, for some time but are now close to completing a deal to sign him initially on loan, with a view to a permanent move.
Salah joined Fiorentina on transfer deadline day in February from Chelsea and scored seven goals in 12 appearances to help them finish fourth in Serie A.
“We are working on it,” Fiorentina president Andrea Della Valle said to the Italian press.
“It’s the crucial day and I’m personally optimistic.
“Of course, in football anything can happen but we will see what the outcome is tonight.”
Chelsea signed Salah in January 2014 on a five-and-a-half-year contract from Basle, but the 23-year-old has not found a place in Jose Mourinho’s plans, making just six Premier League starts and 19 appearances overall.
Fiorentina, meanwhile, recently appointed the former Swansea boss Paulo Sousa as their new head coach after sacking Vincenzo Montella.