Jared (18), a year 13 pupil at Dunstan High School, was one of four New Zealanders selected to compete against the best chemistry pupils from around the world.
More than 250 young scientists from 65 countries took part in the Olympiad, which was held at Cambridge.
All four of the New Zealanders earned medals, three winning bronze, and one silver.
Mentor Robert Maclagan, of Canterbury University, who accompanied the national team, said 61% of the young scientists at the event won medals.
Gold medals were awarded to the top 11%, silver to the next 20% and bronze to the next 30%.
"It was an excellent result for New Zealand, and showed that this country can punch above its weight, which is great," Dr Maclagan said.
Jared arrived home on Wednesday night and admitted to being surprised at winning a medal.
"I didn't think I'd done very well."
The pupils completed an all-day practical exam and a theory exam as well.
The results were announced at the historic King's College antechapel at Cambridge.
"We didn't know how we'd done until we heard our names read out.
"First they read out all the names for the participation medal, in alphabetical order, and none of our names were called, and then they went through the highly commended names," Jared said.
"We were really happy then, because none of our names were read out in those lists, so we knew we must have got medals."
Meeting Nobel Prize winner Sir Harry Kroto was another highlight, he said.
Sir Harry won the Nobel Prize in Chemistry in 1996.
The Olympiad began on July 18 and finished on Monday.
Jared's next focus is scholarship exams later this year and he plans to study engineering at Canterbury University next year.
