Villarreal paid £7m for Kromkamp in the summer but he has failed to settle in Spain and has only made six La Liga appearances for the conquerers of Everton.
The deal is dependent on both Kromkamp and Josemi agreeing personal terms with their new clubs but if they do the transfer will be a straight swap with no cash payments.
Rafael Benitez has confirmed the transfer, saying: "We have an agreement with Villareal and now we have to talk with the two players. He's an offensive right full back but Villareal need to be stronger in defence."
Click here to listen to Benitez's comments during the press conference