This special issue of the Bulletin of the Korean Chemical Society (BKCS) is dedicated to commemorating the life and scientific legacy of the late Professor Hyun-Joon Ha, who passed away in February 2024. Professor Ha served as the 51^st President of the Korean Chemical Society in 2018 and 2019, making significant contributions to the advancement of the chemical sciences in Korea. He was widely recognized for his pioneering research in aziridine ring-opening reactions, the development of radiopharmaceuticals and contrast agents, and studies on the enantioselectivity of lipase-catalyzed transformations. In addition to his remarkable scientific achievements, Professor Ha played a key role in strengthening the Korean chemical community through his leadership and dedication. This memorial issue features a collection of cutting-edge research articles that reflect and honor Professor Ha’s profound influence on the field of chemistry.