Dr. Johannes Lützenkirchen has been involved in surface complexation modelling for nearly 25 years. Starting with his PhD studies in Strasbourg (France), influenced by co-workers of Werner Stumm (aquatic chemistry), continuing with a post-doc in Umea (Sweden) in an environment that combines influences of Lars Gunnar Sillen (solution speciation) and Paul Schindler (surface complexation), and subsequently gaining some insight in consulting at Colenco (Baden, Switzerland) related to nuclear waste disposal with focus on long term safety assessment, he has currently been employed at KIT for more than 15 years. At the Institute for Nuclear Waste Disposal (INE), he is mainly involved in surface studies and to some extent in reactive transport modeling. On web-of-science he presently has more than 90 publications. He has edited one book, and written several book chapters. His main research interests and activities continue to be directed at understanding solution and mineral surface reactions of dissolved radionuclides. He has also some interest in fundamental studies on water solid interfaces and water structure.