The Dutch winger, who has also represented Real Madrid during a distinguished career, is said to be excited about returning to England following a spell in Russia with Alania Vladikavkaz.
Drenthe spent the 2011/12 campaign on loan at Goodison Park, offering him a taste of life in the Premier League.
If he is to link up with Reading, his first task will be to try and return the Royals to the top flight.
Anton Zingarevich has outlined ambitions plans to bounce the club back into the big time at the first time of asking, and adding a player of Drenthe's undoubted ability would be some signal of intent.
The 26-year-old's representative Fabian Veldwijk told NUsport: "The contract has been signed.
"A few small things have to be arranged before it's official.
"He has a good feeling with the club and wants to play in England."