Iranian President Hassan Rouhani is going to deliver a speech at the congress, a son of the late cleric, Mohsen Hashemi, told Tasnim on Sunday.
He noted that First Vice-President Eshaq Jahangiri and Hassan Khomeini, grandson of late founder of the Islamic Republic Imam Khomeini, will also address the commemorative gathering.
Ayatollah Rafsanjani was laid to rest at the mausoleum of Imam Khomeini south of Tehran in January 2017.
He was an influential figure in a campaign led by Imam Khomeini that resulted in the victory of the Islamic Revolution in 1979. The deceased became president for two terms and was the chairman of the Expediency Council for some 20 years.