Journal Thermal Science informed international scientific community about unex-pected death of Prof. Naim Afgan, by publishing short In Memoriam, in our last issue No. 6B, Vol. 23, in 2019. Since, our Publishing plan for 2020 included publishing Special issue with set of selected papers presented at the 14th SDEWES Conference held from October 1-8, 2019 in Dubrovnik, Croatia, we proposed to the Chief Guest Editor Prof. Neven Duić, to devote this issue to Ninety years of the scientific activity of Prof. Naim Afgan, as a tribute his significant contribution to thermal processes investigations, and also due to his contribution and involvement in activities that as a result had organisation of the 1st Conference on Sustainable Development of Energy, Water, and Environment Systems (SDEWESS) in Dubrovnik in June 2002.