The standardization of weights, measures, names and symbols is essential to the continued success of the scientific enterprise and to the smooth development and growth of international trade and commerce.

This desire for international cooperation among chemists and facilitation of the work of the international, but fragmented, chemistry community, were the earliest characteristics of the Union. The creation of IUPAC (1919) succeeded its predecessor body, the International Association of Chemical Societies (IACS), that was born in Paris in 1911, and produced a set of proposals for the work that the new Union had to pursuit.


These included:

  • Nomenclature in chemistry;

  • Standardization of atomic weights;

  • Standardization of physical constants;

  • Editing tables of constants;

  • Development of chemical documentation;

  • Standardization of publications;


If 1911 might now seem an early date for chemists to start talking about the possibility of and need for international collaboration and standardization in Pure Chemistry, previous meetings were held as the first Congress of chemists, in Karlsruhe in 1860 to define the atom and the molecule, then the first international one on organic chemical nomenclature in Geneva in 1892. Jointly, the international congresses on Applied Chemistry stood up since 1894 to 1912.


In 1919, taking over from IACS, IUPAC wanted to link the pure and applied aspects of chemistry. It intended « to organize a permanent cooperation between the chemical associations of the adhering countries, to coordonate their scientific and technical resources, to contribute to the progress of chemistry in all aspects of its field (1919 statutes) »

Commissions worked towards these goals, each one into a particular field.  Consequently, in the interwar period, IUPAC provided a standardisation of several of these topics, contributing to the establishment of a common language.

After the Second World War, IUPAC reorganized regularly, accompanying or encouraging the advent of new chemical sciences sectors, called to become full disciplines.

Meanwhile, it extended its action to numerous other countries. In 1919, five countries started the Union (FR, GB, BE, US, IT) ; in 1921, they are 21. On the threshold of the XXIth century, 45 national organizations adhered, and 16 other ones were affiliated.

In the fifties, the Union undertook a vast communication effort by publishing the results of its work and recommendations: the « colours » books, a Pure and Applied Chemistry specialized magazine, a newsletter, and later an International Chemistry magazine.

At the beginning of the sixties, jointly with IUPAP (Ottawa 1960), the Union adopted the isotope carbon-12 (Montréal 1961) as the unique reference for atomic masses. Then the two agencies, jointly with ISO, gained in 1971 official recognition of the mole as the base unit in the International System of Units (SI) for amount of substance.


The Union, with its international vocation, working towards a common language in chemistry and a transmission of its standards, is in continuity with the first congress in Karlsruhe in 1860, and the International Association of Chemical Societies (1911-1919).


Under its auspices, the first international congress after-World War I took place in Madrid in 1934, jointly with the International Chemistry Conference, today known as the General Assembly of the Union. Ever since, tradition continues.