This book has been designed to provide relevant and the best study material for the preparation of Indian National Chemistry Olympiad (INChO) conducted by the Homi Bhabha Centre for Science Education. The book is equally useful for National Standard Examination in Chemistry(NSEC) and other Chemistry Olympiads. This book has been designed to give the students an insight and proficiency into almost all the areas of Chemistry asked in various Chemistry Olympiads. The present book has been divided into 10 chapters namely Atomic Structure Chemical Equilibrium Chemical Kinetics and Radioactivity Chemical Energetics and Chemical Thermodynamics Gaseous State Redox Reactions and Electrochemistry Solutions Biomolecules Organic Chemistry I and Organic Chemistry II each sub-divided into number of topics as per the syllabi of the INChO. The book contains complete theory exactly on the pattern of INChO and NSEC. Ample number of solved examples designed according to the pattern and the level of Indian National Chemistry Olympiads have been provided in the book. Also unsolved practice problems for both INChO and NSEC have been provided in the book to help aspirants revise the concepts that are asked in the Chemistry Olympiads. Chapter wise coverage of all the questions of INChO and NSEC from2000-2018 has been provided in the book. Each chapter has two level exercises divided according to NSEC and INChO. Problems from recently held Olympiads have also been given in the book. The book also contains 2014-2018 solved papers of NSEC and INChO with detailed and authentic solutions for comprehensive understanding of the concepts on which the questions were based. As the book contains ample study as well as practice material it for sure will help aspirants score high in the upcoming Indian National Chemistry Olympiad 2018.