Thomas M. Connelly, Jr. is the Executive Director and CEO of the American Chemical Society. Prior to joining ACS, he served as Chief Science and Technology Officer, and then as Chief Innovation Officer for the DuPont Company. In these roles, he was responsible for science and technology, with special emphases on polymer science, chemical process development, and later, bioprocessing for chemical synthesis and production. At DuPont, Dr. Connelly led R&D organizations and businesses, while based in the US, Europe and Asia.

Dr. Connelly graduated with highest honors from Princeton University with degrees in Chemical Engineering and Economics. As a Winston Churchill Scholar, he received his doctorate in chemical engineering from the University of Cambridge. In 2016, Dr. Connelly was elected to the National Academy of Engineering. He has served in advisory roles to the U.S. Government and the Republic of Singapore.