Latvijas Pasts issued a souvenir sheet with one stamp commemorating the 150th anniversary of Paul Walden.
Paul Walden was a Latvian-German chemist known for his work in stereochemistry and history of chemistry. His first scientific results were obtained in Riga under the supervision of Nobel prize winner Professor Wilhelm Ostwald. In 1896 he discovered his famous stereochemical reaction, later called the "Walden inversion". He also synthesized the first room-temperature ionic liquid, ethylammonium nitrate.
150th anniversary of the birth of Paul Walden is included in the UNESCO Celebrations Day Calendar for Year 2013.
Every three years, starting in 1988, a Paul Walden medal has been awarded in Chemistry and Science History (both beloved Walden's scientific disciplines) by the Riga Technical University. In 1997 Prof. Edwin Vedejs (Michigan State University, USA) was awarded this medal, which was a starting point for traditional Paul Walden Symposiums.