TASKS FROM THE PREVIOUS ICHO'S

The competition tasks from the past International Chemistry Olympiads (1968 – 2013) are compiled in the publication:

THE COMPETITION PROBLEMS FROM THE INTERNATIONAL CHEMISTRY OLYMPIADS
Editor: Anton Sirota
Issued by IChO International Information Centre and IUVENTA, Bratislava, Slovakia

This publication is presented in three volumes:
1. The competition problems from the International Chemistry Olympiads, Volume 1, 1st – 20th IChO, 1968 – 1988, Bratislava, 2008, 405 pp. (pdf, 4.3MB)
2. The competition problems from the International Chemistry Olympiads, Volume 2, 21st – 40th IChO, 1989 – 2008, Bratislava, 2009, 734 pp. (pdf, 9MB)
3. The competition problems from the International Chemistry Olympiads, Volume 3, 41st – 45th IChO, 2009 – 2013, Bratislava, 2014, 285 pp. (pdf, 5MB)

Best tasks (1980-1990) (pdf, 120KB)

More details you can find here.