William Barbey was born on 14 July 1842 at Genthod in the canton of Geneva.
He studied science at the Academy in Geneva and then engineering at the École Centrale de Paris.
He married Caroline, the daughter of the prominent botanist Edmond Boissier.
After his marriage, he studied botany and undertook botanical research in Spain, Palestine, Greece and Asia Minor.
However, as a supporter of Sunday observance, he insisted that the trains did not run on that day.