Odubajo completed a medical and agreed a three-year contract with the Tigers after they activated his £3.5m release clause.
But the transfer has yet to be finalised with Hull keen to complete a double signing, worth a combined £9m, which would see Gray join Odubajo at the KC Stadium.
Sky sources understand Brentford are yet to decide whether they will accept the offer for Gray, while it is also understood an unnamed Premier League club have matched Odubajo’s release clause.
Midfielder Odubajo was a regular last season following his £1m move from Leyton Orient, helping Mark Warburton’s side secure fifth place in the Sky Bet Championship.
Forward Gray made the move to Griffin Park on the same day as Odubajo – June 27, 2014 – after joining from then-Conference champions Luton for £500,000.
In his debut campaign at Griffin Park, Gray scored 18 goals in 50 appearances.