Prof. Naim Hamdia Afgan (1929-2019) joined the VINČA Institute of Nuclear Science, Belgrade in 1957, where he has spent most of his academic career. His profession-al career was a very successful and fruitful one, but he was also a great professor, educator, humanist and intellectual who, as a magnet, brought together young students, engineers and researchers, and selflessly assisted and directed them in research activities and their profes-sional and scientific development. In his academic career, he has been a scholar, scientist, and engineer. He was also a chair for Energy Engineering at the Mechanical Engineering Faculty, University of Zagreb and a visiting professor at the Instituto Superior Tecnico, Lisbon, Portugal, as well as a United Nations Educational, Scientific, and Cultural Organi-zation (UNESCO) Chair Holder for the UNESCO Chair for Energy Sustainable Manage-ment at the Instituto Superior Tecnico, Lisbon. He has specialized in Sustainability As-sessment methods, and he has authored numerous articles and a book on the theme. Alto-gether, Prof. Afgan published more than 200 papers. Prof. Naim Afgan was one of the founders of the International Center for Heat and Mass Transfer (ICHMT), founded in 1968 in VINČA Institute, and served as the scientific and general secretary of ICHMT for a num-ber of years. Together with Prof. Neven Duić, he was the initiator and one of the founders of SDEWES Conference series in Dubrovnik, and SDEWES Centre in Zagreb. He has also served as the UNESCO expert for development of distant learning methodology. Prof. Af-gan was a Member of the Configuration Control Board of the Encyclopedia of Life Support Systems. He was a Fellow of the Islamic Academy of Sciences, Member of the Academy of Sciences and Art of Bosnia and Hercegovina and Fellow of the World Academy of Art and Science. Many scientists in Belgrade, Zagreb, Lisbon and in many other scientific centres in different countries started their scientific career under supervision of Prof. Naim Afgan. Especially scientific community in Institute of Nuclear Sciences VINČA are thankful for his large contribution to organization and realization of many high quality fundamental and applied research programs devoted to investigation of processes in nuclear and conventional energy systems.