IChO Problems and Solutions
First held in 1968 in Czechoslovakia, between three countries: four theory tasks, no experiment and no medals. It now runs a theoretical and a practical exam, and every host publishes a preparatory problem booklet months in advance.
2026
Uzbekistan
2025
United Arab Emirates
- 1Isocaryophyllene, clovene, and humulenenot published
- 2Rapamycin - A molecular gluenot published
- 3Lanterns and the Burj Khalifanot published
- 4The life of tennis ballsnot published
- 5Solar-powered multi-stage flash desalinationnot published
- 6Solar energy conversion by CO2 reductionnot published
- 7Dubai crude oilnot published
- 8Carbon monoxide: Deadly poison or promising therapeutic agent?not published
- 9Enzymes and cofactorsnot published
- 10A complex problemnot published
- 11Exploring the AminOasisnot published
- 12Rf you ready to spot the answers?not published
2024
Saudi Arabia
- 1Ammonianot published
- 2Electronic nosenot published
- 3Tyrosinasenot published
- 4Potassiumnot published
- 5Unknownnot published
- 6Penicillinnot published
- 7Sabicnot published
- 8Safflowernot published
- 9Porphyrin complexesnot published
- 10Indicatorsnot published
- 11Titration on a balancenot published
2023
Switzerland
- 1Molecular Imagingnot published
- 2Electrochemical CO2 Reductionnot published
- 3Artificial Photosynthesisnot published
- 4Fluorinated and Hypervalent Compoundsnot published
- 5Hydrodesulfurizationnot published
- 6Direct Conversion of Methane to Methanolnot published
- 7Enzyme Kineticsnot published
- 8Nazarov Reactionnot published
- 9Electrolysis in Organic Synthesisnot published
- 10Switzerland - The Country of Pharmaceuticalsnot published
- 11Organic Synthesis: Bleach, a Chameleonic Reagentnot published
- 12Titration Tangonot published
- 13Beauty in Simplicitynot published
2022
China
- 1Rapid and Visual Nucleic Acid Testing for COVID-19not published
- 2Chromium in Ancient and Modern Timesnot published
- 3Capture and Transformation of Carbon Dioxidenot published
- 4A New Journey for Ancient Sulfurnot published
- 5Interconversion among Nitrogen Oxidesnot published
- 6Enabling Phosphinesnot published
- 7Organic Molecules in Lifenot published
- 8Amazing Chiral Spiro Catalystnot published
- 9Total Synthesis of Capitulactonenot published
2021
Japan
- 1Hydrogen at a Metal Surfacenot published
- 2Isotope Time Capsulenot published
- 3Lambert-Beer Law?not published
- 4The Redox Chemistry of Zincnot published
- 5Mysterious Siliconnot published
- 6The Solid-State Chemistry of Transition Metalsnot published
- 7Playing with Non-benzenoid Aromaticitynot published
- 8Dynamic Organic Molecules and Their Chiralitynot published
- 9Likes and Dislikes of Capsulenot published
2020
Turkey
- 1Two Beauties of Turkey: The Van Cat and the Ankara Catnot published
- 2A Tale of a Reactive Intermediatenot published
- 3(±)-Coerulescinenot published
- 4Symmetry Does Matter!not published
- 5Konya, Carrot, Beta-Carotene, Vitamin-A, Immune System, Visionnot published
- 6Thermodynamics through an Interstellar Journeynot published
- 7Phthalocyaninesnot published
- 8Boron Compounds and Hydrogen Storagenot published
- 9Quantification of Heavy Metal Ionsnot published
2019
France
- 1Infinite well and butadienenot published
- 2Hydrogen production by water-splittingnot published
- 3About silver chloridenot published
- 4From black powder to the discovery of iodinenot published
- 5Complexes for the formation of nanomachinesnot published
- 6Characterization of a block-copolymernot published
- 7Ring motion in a [2]catenanenot published
- 8Identification and synthesis of inositolsnot published
- 9Synthesis of levobupivacainenot published
- 10Greening the oxidation of nitrobenzaldehydenot published
- 11The iron age of winenot published
- 12Wine for keepingnot published
2018
Slovakia & Czech Republic
- 1DNAnot published
- 2Repatriation of remains in the middle agesnot published
- 3Emerging electro-mobilitynot published
- 4Column chromatography of radioactive coppernot published
- 5Bohemian garnetnot published
- 6Let’s go mushroomingnot published
- 7Cidofovirnot published
- 8Caryophyllenenot published
- 9Haloform reaction with bleachnot published
- 10A glowing clock reactionnot published
- 11Mineral water identificationnot published
2017
Thailand
- 1Production of propene using heterogeneous catalystsnot published
- 2Kinetic isotope effect (KIE) and zero-point vibrational energy (ZPE)not published
- 3Thermodynamics of chemical reactionsnot published
- 4Electrochemistrynot published
- 5Phosphate and silicate in soilnot published
- 6Ironnot published
- 7Chemical Structure Puzzlesnot published
- 8Silica Surfacenot published
- 9Into the Unknownnot published
- 10Total Synthesis of Alkaloidsnot published
- 11Twist & Chiralitynot published
- 12Acid-base indicator and its application for pH measurementnot published
- 13Calcium iodatenot published
- 14Elaborating Carbon Frameworknot published
2016
Georgia
- 1Problem 1not published
- 2Problem 2not published
- 3Problem 3not published
- 4Problem 4not published
- 5Problem 5not published
- 6Problem 6not published
- 7Problem 7not published
- 8Problem 8not published
- 10Determination of fluoride and chloride content in mineral waternot published
- 11Identifying flavors and fragrancesnot published
2015
Azerbaijan
- 1New and well-forgotten old refrigerantsnot published
- 2Coupling of chemical reactionsnot published
- 3Two binding centers – competition or cooperation?not published
- 4From one yellow powder to another: A simple inorganic riddlenot published
- 5Indispensable glucosenot published
- 6Bread is the stuff of lifenot published
- 7Not by bread alonenot published
- 8Oil for Life and Life after Oilnot published
- 9Tuning bromination selectivity by catalysisnot published
- 10Analysis of the solution of a chromium – vanadium alloynot published
- 11Kinetic determination of Diclofenac (DCF)not published