Hrvoj B. J. Vančik (Varaždin, Croatia, 1952) is professor of chemistry at the Faculty of Science, University of Zagreb, Croatia. His scientific activity comprises the study of organic reaction mechanisms, especially thermally induced reactions in solid-state. Most of his work belongs to the field of vibrational structures of carbocations and solid-state reactions of nitroso and polynitroso compounds. His work in philosophy of science is focused on the theory of complexity in chemistry.