Twenty of the original Grade 8 students from 1977 joined those from the 80s and 90s for a three-day celebration, neatly coinciding with Mount Isa Rodeo.

Celebrations began with a gallop on Thursday at Mailman Races, and a nine-hole golf day at Mount Isa Golf Club on Friday.

On Saturday the group met at their old school on Abel Smith Parade, where Spinifex Senior Campus now resides.

Welcome to Country was performed by Valerie Von Senden, before Spinifex Principal and former KSHS Principal, Phil Sweeney, addressed the crowd.

“We certainly are on Kalkadoon land, and we welcome you back,” Mr Sweeney said.

Mr Sweeney came to Mount Isa in 1992 and was principal of KSHS until it changed to Spinifex Senior in 2001.

Mr Sweeney explained the amalgamation of KSHS and Mount Isa High School in 2001, citing low enrolment numbers for both.

He explained some of the changes over the years including a focus on engineering and trade, the TAFE school, and losing the school library in a fire.

“It took us about six years to get rid of the green, by the way, and that horrible brown that was in the classrooms,” Mr Sweeney laughed.

After speeches, the students were able to look through old photo albums and school journals, and meet their long-lost pals.

Mayor Joyce McCulloch and Councillor Peta MacRae joined the group for a walk-through of the now mostly unrecognisable campus.

Fuelled by nostalgia, alumni then relocated to The Overlander Hotel for a sit-down dinner, drinks, and music, followed by group photos.

Brett Peterson had the old metal archway sign revamped for the reunion, with a fresh lick of green and yellow paint.

The sign was on display at the Overlander, but has yet to find a permanent home.

Former first year student and reunion organiser, Paul Shorthouse, was thrilled with the turnout.

“It's a real homecoming for them, as well as a 40-year celebration for the school,” Mr Shorthouse said.

A minute’s silence acknowledged any students that have since passed.