Ultimate Guide to USNCO in 2026

The US National Chemistry Olympiad (USNCO) is one of the best opportunities for US high school students to do chemistry at the highest level. What makes it stand out is both its difficulty and its prestige. Doing well qualifies you for a training camp, from which participants are selected for the US team at the International Chemistry Olympiad (IChO). It also signals to top universities that you can handle some of the most demanding academic environments in the world. This guide helps you perform as well as possible.

Eligibility and Registration

Eligibility Criteria

To be eligible for the USNCO, students must:

1. Academic standing: be enrolled in high school (grades 9-12) in the United States. Home-schooled students are eligible if they meet equivalent standards.
2. Age: be under 20 years old on July 1 of the competition year.
3. Citizenship and residency: U.S. citizenship isn’t strictly required, but you must be a legal resident attending a U.S. high school. This includes students on F-1 visas and other international students living in the country.
4. Previous participation: students who have represented the US at the IChO can’t compete in the USNCO again. Prior USNCO participation without advancing to the IChO does not disqualify you.

The most important eligibility factor is earning a qualifying score on the local exam, the competition’s “open” round. The cutoff changes year to year, with about 1,000 students invited to the USNCO national exam each year from a pool of roughly 10,000 local test-takers.

Registration Process

Registration usually begins at the school or local level:

1. School registration: schools first register for the Local Chemistry Olympiad, usually coordinated by a chemistry teacher acting as exam coordinator.
2. Local section exams: administered by ACS Local Sections. Contact your chemistry teacher or local ACS section for registration details and dates. The local exam is typically held in March and is multiple choice across many chemistry topics.
3. Advancement to the national exam: top performers are nominated by their local section to take the National Chemistry Olympiad Exam. Each section’s number of nominees follows ACS guidelines. The national exam usually takes place in April and has three parts: multiple choice, free response, and a lab practical.
4. Fees: there may be a nominal fee for the local and national exams. Schools or local sections may help with these or offer financial aid.
5. Results and selection: national exam scores select the top 20 students, who attend a rigorous two-week study camp. From there, the top four are chosen to represent the US at the IChO.

Structure

Local Chemistry Olympiad Exam

The journey begins with the Local Chemistry Olympiad Exam, the preliminary qualifying round:

1. Focus and format: it covers general, organic, physical, and analytical chemistry, and is multiple choice with a set time limit (around 110 minutes).
2. Content and difficulty: questions range from basic to advanced, requiring a strong grasp of fundamentals and the ability to apply them. Calculators are generally allowed, but confirm with your coordinator.
3. Scoring and advancement: correct answers earn points, and incorrect answers usually carry no penalty. The top scorers, usually the top 1,000 to 1,200 nationwide, advance to the USNCO national exam.

USNCO National Exam

Students who excel locally move on to the more comprehensive national exam:

1. Format and content: three parts (multiple choice, free response, and a lab practical), covering organic, inorganic, physical, and analytical chemistry.
2. Free response and lab: the free-response section asks for detailed solutions and explanations, and the lab practical tests hands-on skills, from designing experiments to analyzing data.
3. Scoring and selection: national exam scores select the top 20 students, who are invited to an intensive two-week study camp.

Topics to Study

There are two sets of topics. First, study the areas on the local Olympiad. Then study the additional, more advanced areas on the USNCO national exam.

Local Chemistry Olympiad Topics

1. General chemistry: atomic structure, periodic trends, chemical bonding, stoichiometry, states of matter, chemical reactions, thermochemistry.
2. Organic chemistry: functional groups, nomenclature, basic reactions, stereochemistry.
3. Physical chemistry: gas laws, solutions, thermodynamics, kinetics.
4. Analytical chemistry: acid-base titrations, redox reactions, electrochemistry.

USNCO National Exam Topics

Beyond the local topics, you’ll need to dig into more advanced areas:

1. Advanced organic chemistry: reaction mechanisms, synthesis and retrosynthesis, spectroscopy (NMR, IR, MS).
2. Advanced inorganic chemistry: coordination chemistry, transition metals, crystal field theory.
3. Advanced physical chemistry: quantum chemistry, statistical mechanics, surface chemistry.
4. Advanced analytical chemistry: instrumental analysis, chromatography, spectrophotometry.
5. Biochemistry: amino acids and proteins, enzyme kinetics, metabolic pathways.

Conclusion

If you’re interested in chemistry, you’ve probably thought about doing research in the field as well as competing in it. One way to pursue that is the International Research Olympiad. This nonprofit competition had over 1,000 participants last year and an in-person finals event at Harvard University. The Olympiad aims to assess research ability on merit.

Full disclosure: While I am on the board of the IRO, I do believe that it is a genuinely valuable competition. Board members are not compensated monetarily by the IRO.