Three Year 11 Taradale High School students achieved Scholarship Chemistry, a feat principal Stephen Hensman said was likely unprecedented.
Chemistry teacher Martyn Williams said the performance by Nicola Shepherd, Brandon Huang and Lachie Calder was "exceptional".
"They have achieved at the highest level, where they are competing against the cream of Year 13s from around the country - it is a pretty amazing feat by these guys," he said.
The New Zealand Qualifications Authority said scholarship candidates were expected to demonstrate "high-level critical thinking, abstraction and generalisation, and to integrate, synthesise and apply knowledge, skills, understanding and ideas to complex situations".
"They were doing NCEA Level 1 in Year 10 and it wasn't challenging enough, so part way through last year they were put into Year 12 chemistry classes - so they didn't even finish a full Year 12 chemistry course before they did the Year 13 chemistry class, which makes it even more remarkable."