In 1880 Ostwald began his teaching for decades as a private lecturer at the Chemistry Institute in Dorpat. In the same year he married his fiancée Helene von Reyher. The marriage produced two daughters and three sons. In 1882 Ostwald was appointed professor at the Riga Polytechnic, where he continued his teaching and research on the application of the law of mass effect.
In 1887, the Saxon Ministry of Education appointed Ostwald to the chair of physical chemistry at the University of Leipzig, the only one of its kind in the world at this time. For more than two decades, Ostwald taught and researched here, trained numerous German and international students and maintained close contact with scientists in Europe and North America. In addition to discovering the relationship between degree of dissociation and the concentration of the acid solution (Ostwald’s Dilution Law), he also investigated the energetic approach to the study of physical-chemical processes (Ostwald’s step rule, Ostwald maturation). Also numerous publications were published, such as the textbook “Grundriß der allgemeinen Chemie” in 1889. Moreover, he founded the book series “Ostwalds Klassiker der exakten Wissenschaften”, which republished over 200 elementary original works from all fields of the natural sciences, for example by Helmholtz, Lichtenberg, Kant, Gauss, Euler and many others.
In his research, Ostwald increasingly asked himself the question of how the findings could be applied in the rapidly developing large-scale industry. Since 1894 he has been researching time sequences in chemical processes and the scientific definition of catalysis. He was awarded the Nobel Prize in Chemistry in 1909 for this fundamental work.
With his assistant and later son-in-law Eberhard Brauer, he developped the scientific and technical basis for the production of nitric acid by catalytic ammonia oxidation at platinum contacts in 1901. This laid the foundation for basic processes in the chemical industry for the production of fertilizers, dyes and explosives.
An invitation to the University of Berkeley/ California led Ostwald to the USA for the first time in 1903. In 1905 he became the first German official exchange of scientists to travel to the United States as part of a newly established German-American exchange of scientists and lectured at Columbia University in New York, Harvard University in Cambridge, and the Massachusetts Institute of Technology in Boston on physical chemistry and natural philosophy. On personal request, Wilhelm Ostwald was dismissed from his professorship at the University of Leipzig in 1906. He moved to the estate Energie in Großbothen with his family, which he had acquired in 1901. From now on, he worked as a independent scientist in various fields of natural sciences, color research, natural philosophy and science organization. In addition, he chaired many organisations and societies and published a large number of his own and other works.
Wilhelm Ostwald may be seen as one of the last universal scholars. At the same time he was ahead of his time in many areas. He dedicated his life not only to physical chemistry, but also to philosophical, psychological and pedagogical subjects for decades. His interest in energetics, monism, but also in the use of wind energy and the standardization of paper formats testify to a broad spectrum of creative work. His years of research into color standardization led him to a system of ordering colors that was used in different industries. On April 4, 1932, Wilhelm Ostwald died at the age of 78 in a private hospital in Leipzig. He was laid to rest in the quarry of his country estate Energie in Großbothen.