It's understood a draft contract is being drawn up by the club.
There had been reports that a deal was in place to make sure Mourinho didn't take a job somewhere else ahead of the decision to sack Louis van Gaal – which was confirmed last night.
Elsewhere, captain Robbie Keane trained with the rest of the Republic of Ireland squad at the open session in the Aviva this morning.
James Mc Carthy and Ciaran Clark sat out the session.
McCarthy is carrying a groin and thigh injury but it's not yet known what the issue with Clark is.
Ireland face Netherlands this Friday at the Aviva in our second last Euro 2016 warm up.
