Espanyol and Getafe were linked with a move for Valdez but Rubin Kazan ended up winning the race for the 27-year-old.
Rubin Kazan will pay around €5million for Valdez, who has signed a four-year contract with the club.
Valdez joined Hercules from Borussia Dortmund in the summer of 2010.
The Spanish side were forced to cash in on the striker following their relegation to the Segunda division.
