Yukiya Amano, the director-general of the International Atomic Energy Agency (IAEA), will visit Tehran on August 17 in a bid to advance cooperation between the UN agency and Iran.
The IAEA is investigating suspicions that Tehran has carried out research into how to build an atomic bomb.
Tehran says the suspicions are based on false and fabricated information from its enemies, but it has promised to work with the IAEA to clear them up.
Amano's visit comes ahead of an August 25 deadline for Tehran to provide information relevant to the IAEA inquiry.
Western officials say Iranian clarifications would also advance efforts by six world powers to negotiate an end to a decade-old standoff over the Islamic republic's nuclear program.