The U.S. National Chemistry Olympiad (USNCO) is a four-tier chemistry competition run by the American Chemical Society (ACS) since 1984. It moves from a Local Exam each March, through a National Exam in April and a two-week Study Camp in June, to selecting the four-student Team USA that competes at the International Chemistry Olympiad (IChO) each July. It is open to U.S. high-school students, who enter through their local ACS section — and its past papers are among the best chemistry-olympiad preparation resources anywhere.
Quick facts (2026)
| What it is | A four-tier U.S. chemistry competition that selects the national team for the International Chemistry Olympiad |
| Run by | American Chemical Society (ACS) — the world’s largest scientific society — since 1984 |
| Four stages (2026) | Local 27 Feb–16 Mar → National 10–19 Apr → Study Camp 31 May–13 Jun → IChO 10–19 Jul |
| Who can enter | U.S. high-school students, via their ACS Local Section (you do not register with ACS directly) |
| National Exam | Three parts — 60 multiple-choice (90 min) + free-response (105 min) + laboratory practical (90 min) |
| Recognition | Top 50 nationally earn High Honors; the next 100 earn Honors |
| Past papers | In our free pack: 1999–2025, with answer keys |
Dates, eligibility and rules are set by ACS and can change each year — always confirm current details on the official ACS channels before you plan around them.
Who runs it, and why it matters
The USNCO was established by the American Chemical Society in 1984 with a clear purpose: to find the country’s most able high-school chemists and develop them to a standard that competes with the best in the world. Each year roughly 10,000 students sit the Local Exam, more than 1,000 advance to the National Exam, the top 20 are invited to a residential Study Camp at the University of Maryland, and four are chosen to represent the United States at the IChO. In 2025, Team USA won four gold medals at the IChO in Dubai. You can read more on the program’s competition overview and about pages.
The four-tier pathway
The USNCO is a single competition run in four stages, each narrowing the field. You advance by performing — there is no separate application beyond entering the Local Exam through your section.
Inside the National Exam
The National Chemistry Olympiad is decided by a single, demanding exam in April, made up of three parts that test very different skills. What makes it distinctive among chemistry competitions is the third part: a real laboratory practical, judged on bench technique, not just paper knowledge.
Who can enter — and how students outside the U.S. can use it
It is important to be precise here, because it is easy to assume otherwise. The USNCO is for U.S. high-school students, who enter through an ACS Local Section — you do not register with ACS directly, and there is no individual sign-up on a national website. The competition exists to select Team USA.
So what does that mean for a student outside the United States — for example in China? Eligibility and entry are set by ACS and its local sections: this is an official competition for U.S. high-school students, and there is no individual sign-up from abroad on a national website. Whether and how an international student could take part is therefore an ACS matter — confirm it on the official ACS channels rather than assume.
What is genuinely valuable to any serious chemistry student, anywhere, is the USNCO’s past papers (1999–2025) and its published syllabus. These are among the best chemistry-olympiad practice materials in the world — rigorous, well-structured, and free to study. Used under timed conditions, they are an excellent way to build real chemistry depth, whether or not you ever sit the exam itself. Our preparation resources and exams & past papers pages show how to work through them.
How to prepare with the past papers
Strong USNCO performance is built, not improvised. The students who reach the National Exam and beyond tend to do the same things: start months ahead, map the full syllabus end to end, work through years of past papers under timed conditions, and practise the free-response paper and the laboratory work specifically — not just multiple choice. Depth beats last-minute cramming. Even for a student who cannot sit the official exam, that same routine — built around the 1999–2025 paper library — is a serious, structured way to reach a high standard in competition chemistry.
Frequently asked questions
What is the USNCO?
The U.S. National Chemistry Olympiad is a four-tier competition run by the American Chemical Society since 1984, selecting the U.S. team for the International Chemistry Olympiad: Local Exam, National Exam, Study Camp, then IChO.
Who can take part in the USNCO?
U.S. high-school students, who enter through their ACS Local Section (not directly with ACS). For students outside the U.S., confirm any eligibility on the official ACS channels — do not assume you can sign up from abroad.
What is on the National Exam?
Three parts: 60 multiple-choice questions (90 min), a written free-response paper (105 min), and a laboratory practical (90 min) judged on bench technique.
Can international students still benefit from the USNCO?
Yes — its 1999–2025 past papers and syllabus are among the best chemistry-olympiad practice resources anywhere, useful for building real chemistry depth regardless of whether you sit the exam.
This is the U.S. National Chemistry Olympiad (USNCO) information desk, synchronising the official competition information — dates, rules, the syllabus, past papers and results — for chemistry students in China, operated by Hanlin Education. The USNCO is run by the American Chemical Society (ACS), which sets all official rules and eligibility; the information here is synced from the official ACS sources. Always confirm the current details on acs.org. Confirmed errors are corrected within 7 working days.