Walther Hermann Nernst (June 25, 1864 - November 18, 1941) was a German chemist.

Nernst was born in Briesen, Prussia. He studied physics and mathematics at the universities of Zürich, Berlin and Graz. After some work in Leipzig, he founded the Institute for Physical Chemistry and Electrochemistry at Göttingen. In 1920, he received the Nobel Prize in chemistry in recognition of his work in thermochemistry. In 1924, he became director of the Physikalisch-Chemisches Institut in Berlin, a position from which he retired in 1933.

Nernst contributed greatly to electrochemistry, thermodynamics, solid state chemistry and photochemistry. Amongst his most notable discoveries were