"For the first time in three years, we won a gold medal," Le Ngoc Quang, deputy director of the Hanoi's education department, said.
The gold medalist was Tran Xuan Tung, a grade 12 student. Ho Phi Dung, an 11th grader, won a silver medal and 12th grade students Le Tran Dao and Nguyen To Vinh Huy won bronzes.
Their performance saw the country finish 10th out of 39 countries and territories who took part in the competition.
The 2018 Olympiad was held from November 3 to 11 with 214 students competing including from countries highly advanced in astrophysics, astronomy and space science such as Russia, the U.S., China, and India.
Contestants had to take four tests: practice, theory test, data processing, and team.
The Vietnamese consisted of five students from the Hanoi-Amsterdam High School for the Gifted. Founded in 1985 the school is well-known in the country for fostering talents. Its students have won over 77 gold, silver and bronze medals in many international competitions.