Spanish radio station Cadena Ser reported on Monday that the two clubs had agreed terms for the 25-year-old Dutch star.
Reports suggest the fee that has been agreed is around £20million.
A statement from the Dutch club read: “Ajax are in talks with Real Madrid over the possible sale of Klaas Jan Huntelaar to the Spanish club.
“However no deal has been agreed at the moment.”
Huntelaar has been linked with clubs from England, Italy and Spain in recent weeks.
The Holland international has over two-years left on his current contract with the Dutch giants.