German chemist who devoted his life as a teacher, researcher, and editor to the advancement of colloid chemistry.

Ostwald, the second son of Wilhelm Ostwald, spent most of his career at the University of Leipzig, beginning as a zoology student before turning to chemistry; he became a full professor there in 1935. As the editor (from 1909) of Kolloidchemische Beihefte and other journals and as the founder (1922) and president of the Kolloid Gesellschaft, Ostwald exerted international influence in fostering and forwarding research in colloids. His own work included discoveries of electrical and optical properties of colloids.