Norwegian chemist who, with Peter Waage, formulated the law of mass action, which details the effects of concentration, mass, and temperature on chemical reaction rates.

Guldberg was educated at the University of Christiania and taught at the royal military schools before becoming professor of mathematics at the University of Christiania in 1869. His study of chemical thermodynamics preceded his formulation in 1890 of Guldberg's law, which states that on the absolute scale the boiling point of a substance is two-thirds its critical temperature (the maximum at which a gas can be liquefied by pressure alone). In 1864 Guldberg and Waage announced their law of mass action, which drew little attention until it was rediscovered by William Esson and Vernon Harcourt at the University of Oxford in the 20th century.