Salih is a professor of Civil engineering at Khartoum University, Sudan. After his PhD and DIC at Imperial College, London, he returned to Sudan in 1973 and has since worked in various teaching, research and consulting capacities at the University and abroad. These positions include the deputy vice chancellorship of the University; UNESCO's environmental adviser (Arab Region), deputy secretary of the IHP and director of Cairo and Tehran Offices and director of Water Sciences Division in Paris. He initiated regional and international networks on water resources management in arid zones and served as a jury member of many international water prizes. He is a fellow of the African Academy of Sciences and the International Water Resources Association. He is a member of many International Scientific Associations (IAHR, IAHS, etc.).

Hassan holds BSC (1977) & MSC (1983) in Agric Econ from Univ of Khartoum, Sudan & MSC (1988) and PhD (1989) in Economics from Iowa State Univ. He is the ex-director of the Centre for Environmental Economics and Policy in Africa (CEEPA), at the University of Pretoria and previously held positions with CSIR in South Africa, and CIMMYT International. He has served as member of the UN Committee for Development Policy (CDP); Stockholm Environment Institute (SEI) Science Committee; CGIAR Science Council (ISPC); Human Sciences Research Council of SA; CGIAR Climate Change Challenge Program (CCCP) Board; Academic Advisory Panel for The World Development Report on Climate Change; Board of Stockholm Resilience Centre; GEF Science and Technical Advisory Panel (STAP IV); Science Panel of the Millennium Ecosystem Assessment. His honours include, member, Academy of Sciences of South Africa (since 2005); University of Pretoria Chancellor Medal for Research (2011); Four times Univ. of Pretoria “Achiever: Academic Excellence” (2005 to 2014). He is founding chief editor of the African Journal of Agric. and Resource Economics and has published more than 140 refereed publications including 12 books.

Hassan is president of the Sudanese National Academy of Sciences and was president of TWAS from 2019-22; and Chair of the Governing Council of the United Nations Technology Bank for the Least Developed Countries, and of the International Advisory Board of the Centre for Development Research, Germany. He covered many high-level positions, such as President of the InterAcademy Partnership (IAP); founding Executive Director of TWAS; President of the African Academy of Sciences; founding President of the Network of African Science Academies, and Chair of the Council of United Nations University. After obtaining his PhD in mathematics from the University of Oxford, he returned to the Sudan and later became Professor and Dean of the Faculty of Mathematical Sciences at Khartoum University. Among his honours are: Comendador and Grand Cross of the Brazilian Order of the National Scientific Merit, and Officer of the Order of Merit of Italy. He is a member of several scientific academies, including the Belgian, Colombian, Cuban, Moroccan, Pakistani, South African and the Pontifical. He is the recipient of the G77 Leadership Award and of the Abdus Salam Medal for Science and Technology.

Hassan has focused his attention on the genotypic and phenotypic variables concerning hypertension in the Middle East, and a study of the personal and environmental influences on the physical fitness in urban and rural youth of the region. He is professor and chair of physiology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman. He was previously chairman of the department of physiology, King Abdulaziz University, Jeddah, Saudi Arabia. He has received the Pan Arab Hypertension Society Award in 1999 and the Asian Federation Olympic Committee Award in 2000. He is an elected member of the Hypertension Society and fellow of the Royal College of Physicians and Surgeons, Glasgow. Member of the American Academy of Sleep Medicine 2005, Director of the Canadian Health Centre , Muscat Oman 2017