The event will be held at the Orme Suite at Venue Cymru, Llandudno, with tickets costing £7.
There will be a meet and great at 7.30pm followed by a disco at 9.30pm.
Profits from the event will be divided between Ty Hapus Food Bank and St David’s Hospice in Llandudno.
There are only 200 tickets available and the event is ticket only.
The reunion is for anyone who attended Mostyn School on Trinity Avenue up to 1969.
Organiser Linda Groom said: “We have got ex pupils of all school years attending and we have several people travelling long distances to attend.
“Everyone is welcome from any year “
Tickets are on sale from Ty Hapus Community Hub in Ffordd Penrhyn Llandudno 8.30am to 1pm from Mon to Fri or from Linda Groom 07787577352.
“We are very grateful to the Manager of Ty Hapus for assisting with selling tickets,” added Linda.
Also, Linda and Metje De-Kooning will be at Ty Hapus 11am to 1pm every Friday until Sept 15th or until all tickets are sold.
There will be a raffle so any donations of prizes would be very welcome.
Anyone who has any memorabilia or photos an also contact Linda Groom .