Ex-students from around the world including New Zealand are returning home for the official opening of the $1.6 million building.
Secretary of the Tonga College 'Atele ex-students association in New Zealand, Viliami Latu, says majority of the funding for the new facility came from ex-students in the US.
He says the hall replaces the old building that was destroyed by a fire around 10 years ago.
The college's annual general meeting will take place tomorrow, followed by the opening ceremony of the new hall on Saturday by His Majesty King Tupou VI.
The programme will conclude with an inaugural church service on Sunday that coincides with the school's 136th anniversary.