The Hamas prime minister in Gaza, Ismail Haniya, arrived in Tehran on Friday on a three-day trip and is due to speak at a rally marking the 33 anniversary of the 1979 Islamic revolution on Saturday, state media reported.
The state television website said the Palestinian will meet with Iran's supreme leader Ayatollah Ali Khamenei, President Mahmoud Ahmadinejad and other high ranking Iranian political and security officials.
Local media said two days ago that Haniya would receive an honorary degree from Tehran University.
Israel views Hamas as a terrorist group and has accused Iran of being its main arms supplier.
Khamenei, last week called Israel "a cancerous tumour that must be removed, and God willing it will be."
Ahmadinejad, who is to give a speech on Saturday to mark the day 33 years ago when revolutionaries claimed victory over the deposed regime of the US-backed shah, has strongly backed the Palestinian cause.
He has voiced Iran's longstanding policy of rejecting the continued existence of Israel and of supporting foes of the Jewish state, including Hamas.
The Islamist group this week signed a deal with its rival, Fatah, which runs the West Bank under Palestinian president Mahmud Abbas, to form a consensus government ruling both Palestinian territories.
Israel has rejected the union, and warned Abbas to choose between reconciliation with Hamas and making peace with the Jewish state.
A senior Fatah official has told AFP that the new Palestinian government would be announced in Cairo on February 18.