Caro also contributed to the production of combat gases used by German troops during World War I. After the war he became the first president of Bayerische Stickstoffwerke AG.
Caro is the author of many works about various elements, synthesis a chemical compounds actions e.g. Gewinnung von Chlor und Salzaeure (1893), Landwirtschaftliche Untersuchungen (1895), Handbuch für Azetylin (1904), Die Torflager als Kraftquellen (1907).
After Hitler's rise to power he left Berlin, emigrating through Switzerland to Italy. Caro died in 1935 and was buried in Zürich.