A stately green cloak covers his original costume the ascetic camelhair tunic that he wore when preaching the doctrine of baptism on the banks of the Jordan.
Please mention this source: The Ghent Altarpiece: panel John The Baptist detail, by Jan van Eyck; Hubert van Eyck, collection Sint-Baafskathedraal Gent, artinflanders.be, photo: Hugo Maertens, Contractuele beperkingen.