Karol Olszewski (29.01.1846-24.03.1915) was a Polish physicist and chemist and a member of the Polish Academy of Sciences (1888). He was born in Broniszów Tarnowski. He graduated from Heidelberg University (1872). From 1876 he was professor at the University of Kraków.
His research was in the field of low temperatures. In 1883, together with Z. Wróblewski, he obtained liquid oxygen in measurable quantities. He also condensed nitrogen, argon and hydrogen (but could not keep the hydrogen in the liquefied state). He determined the liquefaction temperature and pressure of hydrogen. He improved the liquefaction apparatus, attempted (1896—1905) to obtain liquid helium, reaching in the process a temperature of a few degrees Kelvin, and studied the physical properties of the condensed gases.