He studied the properties of glass, including its strength, and in 1889 presented his doctoral thesis, "Untersuchungen über die Festigkeit des Glases".

In 1894, he accepted a faculty position in mathematics and natural sciences at the University of Fribourg in Switzerland.

[6][7] Mościcki created an electric arc method for fixing nitrogen, and he and Wierusz-Kowalski set up an experimental plant around 1903, trading nitric acid as the Société de l'acide nitrique.

[8] Wierusz-Kowalski's major fields of study were lightning and electrical discharge, luminescence and phosphorescence.

A Section of Experimental Physics was opened in 1916 as part of the Department of Philosophy, under Wierusz-Kowalski's leadership.

[17][18] In January 1919 Józef Wierusz-Kowalski helped to found the Warsaw Physical Society.

[14] In 1919 Józef Wierusz-Kowalski entered the diplomatic service of Poland,[17] and was appointed envoy extraordinary and minister plenipotentiary to the Holy See on 1 July 1919.