After heavy rain in the north-east, the Black Cats' pitch has been deemed unsuitable for purpose and the clash with the Royals will now be rearranged
After a morning of torrential rain on Wearside, referee Neil Swarbrick made the decision to postpone the game at around 13:40 BST.
The Black Cats were busy in the transfer window on Friday signing Steven Fletcher and Adam Johnson, with the decision denying the Scottish striker the chance of a debut against the Royals.
A statement on the north-east club's website confirmed that all tickets for the game would be valid for the rearranged fixture.
Reading announced via their Twitter account: "Nobody arguing with the decision, a sensible choice. Such a shame for our supporters - a massive thank you to all who travelled."
Black Cats midfielder Craig Gardner tweeted: "Gutted games off especially our fans and reading travelling 2 game roll on Tuesday now #itchingtoplay"
His team-mate David Meyler added: "Gutted the games off! Now let's get ready for Tuesday. #hawaythelads"