Chemical reactions on catalytic surfaces play a vital role in many industrial processes such as the production of fine chemicals, drug precursors and artificial fertilisers. In addition, the development of catalytic converters used to make car exhaust cleaner and the production of semiconductors rely heavily on a detailed understanding of processes occurring at surfaces. On awarding Prof. Ertl with the SEK10m (€1.1m) prize for his pioneering research into chemical reactions on solid surfaces, the Swedish Academy of Sciences said his research had "laid the foundations for an entire field of research". Professor Ertl is perhaps best known for determining the detailed mechanism of the catalytic synthesis of ammonia over a solid iron catalyst during the Haber Bosh process as well as the catalytic oxidation of carbon monoxide to carbon dioxide over palladium - the reaction used in catalytic converters. To gain a complete picture of a surface reaction many different experimental techniques need to be used. Because of the sensitive nature of trying to observe how individual atoms and molecules behave on a surface, experiments need to be conducted in advanced high-vacuum equipment. During this research he discovered that photoelectron microscopy could be used to image oscillating changes in surface structure during such surface reactions. He won the Japan Prize in 1992 for his "invaluable contributions to the development of this important and new research area in science and technology of material interfaces". In 1998 Prof. Ertl and Professor Gabor Somoriai of the University of California, Berkeley, USA, were awarded the Wolf Prize in Chemistry for "their outstanding contributions to the field of the surface science in general and for their elucidation of fundamental mechanisms of heterogeneous catalytic reactions at single crystal surface in particular."