Enrique Moles Ormella introduced the study of physicochemistry (the natural science dealing with the relationship between chemical and physical properties of matter) into Spain. He studied this field in Leipzig, with a grant from the Junta para Ampliación de Estudios, and conducted research with Philippe A. Guye. He continued working on physicochemistry throughout his life, until he was not allowed to return to the National Institute of Physics and Chemistry after the Civil War.
After his return from Leipzig in 1911, he has appointed assistant professor in the Faculty of Pharmacy, University of Madrid, where he met two professors that he considered his mentors: José Rodríguez Carracido, and José Casares Gil. In 1927, he obtained the chair of Inorganic Chemistry in the Faculty of Sciences.
Moles put special emphasis on fostering and enhancing the practical teaching of chemistry. He was a member of the Instituto del Material Científico, created by the government to provide research resources to educational and scientific institutions. Moles was also one of those scientists directly responsible for the establishment of the National Institute of Physics and Chemistry. His experience in this field and his knowledge of similar institutions in Europe and America (he visited the United States in 1920) took him, along with Miguel Catalán, a chemist and expert in spectroscopy, and architects Manuel Sánchez Arcas, and Luis Lacasa, to various European institutions in order to design the installations of the National Institute of Physics and Chemistry. Moles also encouraged the construction of new laboratories at the Faculty of Sciences and became a member of the Construction Board of the University of Madrid in 1931.
As a researcher, he won international recognition for his work to measure atomic weights. He believed that it was possible to measure the atomic and molecular weights of the elements relying exclusively on experimental data. The main challenge that researchers had to meet was the difficulty of obtaining accurate measurements, such as temperature, pressure or weight. Moles tackled that challenge and designed highly sophisticated techniques that earned him international recognition.
In 1921, Professor Moureu, president of the International Union of Pure and Applied Chemistry, invited Moles to serve as member of the International Commission on Atomic Weights, with scientists such as Brauner, Guye, Nasini, Richards, and Swarts. He presented Spain at the Conference of the International Union of Pure and Applied Chemistry held in Brussels on 27 June 1921. In 1934, he organized, with the Spanish Society of Physics and Chemistry, the 9th International Congress of Chemistry. In 1951, he was appointed secretary of the International Commission on Atomic Weights of the International Union of Chemistry.
The Civil War was the turning point in Enrique Moles’ career.In 1936, he was professor of Inorganic Chemistry in the Faculty of Sciences in Madrid, was head of a department of the National Institute of Physics and Chemistry, secretary of the Spanish Society of Physics and Chemistry, member of the Academy of Sciences and, since 28 September 1936, vice-rector of the Universidad Central, a position that he could not hold because of the Civil War. At the time of the war’s outbreak, Moles took over the leadership of the National Institute of Physics and Chemistry (Blas Cabrera had moved to Paris). The Republican government needed all the resources for the war effort and used this institution for military purposes. In 1937, he was appointed Director of Explosives. His political posts and the fact that he had signed the manifesto "Against the Fascist barbarity," published by El Socialista newspaper on the day after the aerial bombardment of Madrid, made him the object of serious reprisals upon his return from France in December 1941, after the occupation of Paris (he had escaped to the neighboring country in 1939). He was expelled from the university in January 1944, and joined the Instituto de Biología y Sueroterapia (IBYS) (Ibys) as technical advisor to the department of Pharmaceutical Chemistry.