FAQs of USNCO Information

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The full name of USNCO is the US National Chemistry Olympiad, a multi-tiered chemistry competition for high school students, which is sponsored and hosted by the American Chemical Society (ACS) annually.

USNCO has two rounds, the Local Exam (regional) and the National Exam. Top students from the Local Exam are nominated to compete in the National Exam. The 20 top-scoring students from the National Exam are invited to a two-week-long Study Camp, where the top 6 students are selected by several theoretical and laboratory exams. The top 4 students represent the US to participate in the International Chemistry Olympiad (IChO), while the fifth and sixth place are the first and second alternates, respectively.

The Local Exam is made of 60 multiple-choice questions (MCs), written by the USNCO exam task force and needs to be done in 110 minutes. 

Note: Some Local Sections may shorten the time or add extra questions in addition to the 60 MCQs or use even other methods to nominate students for the National Exam. Please confirm with your Local Section Coordinator for details.

There are 3 Parts in the National Exam, Part I is also made of 60 MCQs questions, but in 90 mins, Part II is 8 written questions in 105 mins, and Part III is 2 laboratory practicals in 90 mins. Typically, the three parts are scheduled on a single day, and the date is determined by each Local Section.

The Local Exam may be held at the contestant’s high school, or a college designated by the Local Section, typically at the college where the Local Section Coordinator works. The National Exam is typically held in a local college as there is a laboratory part.

The national test window for Local Exam in typically the first 3 weeks in March, the exact date is determined by the Local Section Coordinator or even your HS chemistry teacher. The National Exam window is typically 9 days (5 weeks days + 4 weekend days) in mid-April, however, the National Exam 2025 was scheduled in early April, which makes the prep window between Local Exam and National Exam for some Local Sections pretty limited.

USNCO's official website has all Local Exam and National Exam questions and answers from 1999 to present.

Since 2020, Dr. Chen volunteered to initiate and lead the USNCO Exam Annotation Program, which is to explain the multiple-choice questions in a detailed, profound, and educational way! With the support from the USNCO office and the joint efforts of dozens of volunteers from all over the world, annotations of 25 years of Local Exam and National Exam Part I have been published on the USNCO website, including the most recent 5 years (also the most challenging). Other years are under proofreading and will be published soon.

Please click on the Solutions link in the right side of the exam questions to access the annotations.

You can find the coordinator's name and contact information by entering the zip code of your school on the USNCO website.

According to the USNCO Summary Report, before the pandemic, there are about 16,000 students taking the Local Exam and about 1,000 taking the National Exam each year. The number in Local Exam seems dropping after the COVID, though it might be caused by a more accurate counting due to the new centralized registration requested by USNCO headquarter since 2022.

USNCO's Local Exam is organized by each Local Section, so the top students in each Local Section are nominated to compete in the National Exam. 

Note: 1) Only US citizens and permanent residents (green card holders) are eligible for the National Exam; 2) Each Local Section has limited spots (nominees) for the National Exam; 3) No more than 2 students from each school can advance to the National Exam. 

Note: Students who have previously made it to Study Camp can advance directly to the National Exam, which is not counted for the two students from each high school.

The general idea is that each Local Coordinator finds the top two students from each participating school, and then ranks them based on their performances in the Local Exam, and finally nominates the top ones (the number of nominees in each Local Section varies, and can be found in the answer to the next question) to take the National Exam.

The number of each Local Section’s national nominees is proportional to the number of ACS members in the Local Section, which can be found here. 

Note: There seems an increase of 3-5 spots for some Local Sections in 2025, not sure this is a confirmed policy change or a temporary adjustment. 

As the nomination for National Exam is within each Local Section, there is no nationwide cutoff. Each Local Section has its own cutoff based on the number of nominees, and cutoff in each Local Section also varies by year as the difficulty of the exam and the number of participants varies.

Note: Some Local Sections are more competitive than others, which may have a higher cutoff.  Strong performance shown on the award list from your region might be contributed by a few high-performing schools, which doesn't mean the cut-off for your school is high.

Usually, you can email the Local Coordinator (see the question above), but many of them may not answer questions like this. In case the information is not available, you may check the High Honors/Honors list in the past 2-3 years to see the performance of your high school and Local Section in the National Exam. If the region has several students in the High Honors/Honors list each year from different schools, it means that your region may be relatively competitive with a higher cutoff.

Traditionally, students interested in competing must work with their high school chemistry teacher who registers the school to participate in the program. A parent or guardian can contact the USNCO Coordinator at their ACS Local Section only if their school is not participating in the competition.

Home-schooled students should contact the USNCO Coordinator at their ACS Local Section. Home-schooled students participate in the Local Competition with the nearest participating high school.

Since 2022, USNCO headquarter introduced the centralized registration system, that said, all students who are interested in participating in the Local Exam must register through their system with parents' signature, which is typically open in Nov and ends in January. If you unfortunately missed the registration, you may not be able to participate. 

While some high schools or Local Sections that are particularly competitive may have additional school-level preliminary tests or restrictions to select students to take the Local Exam. Contact your chemistry teacher or Local Coordinator for confirmation. 

Note: it seems like there is some conflict between the school-level preliminary test and the centralized open registration system, any questions regarding this may directly go to Local Coordinator or USNCO headquarter.

In general, any high school student in the U. S. may register for the Local Exam (overseas U.S. students may also register through the International Chapters of ACS, detailed info can be found by contacting the USNCO office at usnco@acs.org). Once again, Only U.S. citizens and permanent residents (green card holders) are eligible to compete in the National Exam.

There is no official syllabus for the USNCO exams, a list of Learning Objectives summarized by Dr. Chen can be found here. The Local Exam includes 10 topics, each with 6 multiple-choice questions, as shown below. 

1. 1 – 6 Stoichiometry/Solutions
2. 7 – 12 Descriptive/Laboratory
3. 13 – 18 IMFs/States of Matter
4. 19 – 24 Thermodynamics
5. 25 – 30 Kinetics
6. 31 – 36 Equilibrium
7. 37 – 42 Redox/Electrochemistry
8. 43 – 48 Atomic Structure/Periodicity
9. 49 – 54 Bonding/Molecular Structure
10. 55 – 60 Organic Chemistry/Biochemistry 

The topics in the USNCO exams have a good overlap with AP Chemistry curriculum, except for Descriptive Chemistry and Organic Chemistry/Biochemistry. Compared to the AP Exam, the non-organic topics of the Local Exam covers some more advanced topics, such as solid models, and also require a higher level of quantitative analysis (complex calculations) and conceptual understanding. Part I of the National Exam, similar to the Local Exam, also includes the above 10 topics, but the requirements for quantitative analysis, conceptual understanding, descriptive chemistry, and organic chemistry are further elevated, and the time is shortened from 110 minutes to 90 minutes, which requires a faster speed and higher accuracy. 

Averagely, the National Exam is significantly harder than the Local Exam. According to the unofficial stats in National and Local 2021, the average score of the same group of students in the National Part I Exam is 12 points lower than that in the Local Exam.

Based on the score of their overall performance, some students are recognized with High Honors and Honors and receive a certificate from the USNCO national office.  The top 50 students are recognized as High Honors and the next 100 as Honors. The list of High Honor and Honor students is published on the USNCO website.

To the best of Dr. Chen’s knowledge, the High Honors and Honors Awards are based on a combination the student’s performance in Part I and Part II with a certain formula, such as total score = 1.25×Part I + Part II. The top 20 students are determined by a combination of all of three parts with a certain formula, such as 1.25×Part I + Part II + 0.5×Part III. 

Note: Before the pandemic, the number of Honors Award winners varies by year, but always around 100. However, since 2022, the number of Honors Award is fixed to be 100, which indirectly confirms the formula above. Ranking solely based on Part I may be hard to figure out the exact top 150 students as it is common to have multiple students with the same scores in Part I Exam (MCQs), a combination of Part I and Part II (FRQs) can provide the absolute top winners. You may also notice that a certain number of Honorable Mention are awarded in 2020 and 2021. Those are the two COVID years, when the USNCO National Exam was hosted online, with Part I scheduled in one weekend, and the ~top 200 students from Part I invited to take the Part II in a following weekend. All or some of those Part II qualifiers but didn't get into the top150 list were awarded as Honorable Mention.

Local Exam scores can be obtained from the Local Coordinator. For the National Exam, only student scores for Part I (multiple-choice) are sent to the Local Section coordinators to be distributed to teachers and/or students. 

According to the data of the National Exam 2021, a 50+ in Part I is competitive for Camp, 45+ is competitive for High Honors, 40+ is competitive for Honors. As described above, the Honors/High Honors are not determined by Part I only, so a competitive score in Part II is also needed. 

Note: the exams are getting harder, so the cutoff dropped in 2022-2024. To the best knowledge of Dr. Chen, 33 is the cutoff for Honors in 2023. The National Exam in 2025 is easier, a higher cutoff can be expected.

Google "year" + "USNCO" + "list", generally the first link with a PDF is the High Honors and Honors Award list.