Pennington, 24, is due for a medical with the Tigers today, according to the Liverpool Echo.
It would be the sixth time he has left Everton on a temporary basis, following spells with Tranmere Rovers, Coventry City, Walsall, Leeds United and Ipswich Town.
Though he has featured in pre-season for the Blues, he has not played for the first team in a competitive game since April 2017.
And with Everton still keen on adding a centre-half before tomorrow’s transfer deadline, Pennington is some way down the pecking order.
Still contracted to Everton until June 2021, Pennington will link up with winger Josh Bowler at the KCOM Stadium, who is also on loan at the Tigers from Goodison Park for the 2019-20 season.
He has made nine Everton appearances, scoring one goal.