El-Shall started his academic career in 1986 as a research associate at the University of California at Los Angeles (UCLA) while working with Howard Reiss on vapor phase nucleation and with Robert L. Whetten on molecular clusters and cluster ions. Since 1989, he has been on the faculty of the Chemistry Department, and has served as the Chair of the Chemistry Department at Virginia Commonwealth University (VCU) from 2015 to 2021. He is the Mary Eugenia Kapp Endowed Chair in Chemistry and Commonwealth Professor at Virginia Commonwealth University (VCU).
El-Shall served as a Senior Science Advisor in the Bureau for the Middle East, Middle East Regional Cooperation (MERC) Program of the USAID. He focused on enhancing and expanding joint Arab-Israeli research activities through MERC projects, and has also conducted site project reviews in Israel, Jordan and Egypt to improve collaborative research opportunities across borders and enhance implementation of research results. He also worked on creating new initiatives for young investigators in order to catalyze the next generation of Arab-Israeli research cooperation, and to create long-term sustainable collaborations between Arab and Israeli scientists.