Jules-Émile Verschaffelt was born in 1870 to an educated family in Gent. His brother Éduard would later become a professor of plant science at the University of Amsterdam. Verschaffelt began his university studies in Gent in 1888 and completed the Ph.D. qualifying exam with distinction in 1893.
Although he was of Flemish origin, his education was entirely in French. Professor Mc.Leod influenced him to study the plant sciences and to learn to speak cultivated Dutch. This skill would serve him very well in later life. After passing his Ph.D. qualifying exam, Verschaffelt served as an assistant in the geology department and began his study of physics, crystallography and chemistry. A research project he completed on the refractive index of fluid mixtures won him a 2-year scholarship for studies in the Netherlands. He spent his first year in Amsterdam, taking courses with Van ‘t Hoff and Van der Waals. In 1894, at the beginning of his second year, he joined Kamerlingh Onnes’s laboratory, while taking courses with Lorentz. After his scholarship expired he was hired as a laboratory assistant, and served as such from 1895 to 1898.

Around 1897, Verschaffelt became engaged to a Dutch student of physics, Elisabeth Ebert, and started planning for marriage and for a career in the Netherlands. To this end, he would need a Dutch doctorate. Kamerlingh Onnes accepted him as a graduate student and assigned to him an investigation of the properties of dilute fluid mixtures. He defended his doctoral thesis in 1899, and from 1898 to 1906, he taught high school physics in Dordrecht. During this period, Verschaffelt retained his collaboration with Kamerlingh Onnes.

Verschaffelt was appointed a professor of experimental physics at the Free University of Brussels in 1906. When the First World War erupted in 1914 and the Germans occupied Belgium, he and his family escaped to the Netherlands. Kamerlingh Onnes appointed him to a research position at the Cryogenic Laboratory in Leiden, and he taught high school again to supplement the family income. Lorentz, then secretary of the Holland Society of Arts and Humanities (HMW), appointed him as the French-language editor of the Archives Néerlandaises. For many years he also served as a science secretary for the Institut International de Physique Solvay. This required thorough knowledge of French, German and English, and brought him a huge amount of work.

In 1923 he received an appointment from the University of Gent, which had recently turned Flemish. He became a full professor in 1929 and served until his retirement in 1940. Verschaffelt remained in Belgium during the Second World War. When the Flemish movement compromised itself by seeking German support for its cause, Verschaffelt refused an honorary membership. As a consequence he spent some months in jail in 1943. In 1946, after his wife’s death, he left for the Netherlands. Throughout his long career and up to the year of his death, he published almost 300 papers on topics of thermodynamics, capillarity, thermochemistry and irreversibility. He became a correspondent of the Belgian Academy in 1909.