(Mexico/US) was a co-recipient (along Paul J. Crutzen and F. Sherwood Rowland) of the 1995 Nobel Prize in Chemistry for his role in elucidating the threat to the Earth’s ozone layer of chlorofluorocarbon gases. Between 1974 and 2004, he held research and teaching posts at the University of California, Irvine, the Jet Propulsion Laboratory at Caltech, and the Massachusetts Institute of Technology (MIT) where he held a joint appointment in the Department of Earth Atmospheric and Planetary Sciences and the Department of Chemistry.

On July 1, 2004, he joined the Department of Chemistry and Biochemistry at the University of California, San Diego, and the Center for Atmospheric Sciences at the Scripps Institution of Oceanography. He is a member of the Pontifical Academy of Science, United States National Academy of Sciences, United States Institute of Medicine, and The National College of Mexico. He serves on the boards of several environmental organizations and also sits on a number of scientific committees, including the U.S. President's Committee of Advisors in Science and Technology, the Institutional Policy Committee, the Committee on Global Security and Sustainability of the John D. and Catherine T. MacArthur Foundation, and the Mario Molina Center.

He has also received more than 18 honorary degrees. Asteroid 9680 Molina is named in his honor. After completing his basic studies in Mexico City and Switzerland, Dr. Molina earned a bachelor's degree in chemical engineering at the National Autonomous University of Mexico in 1965; a postgraduate degree from the Albert Ludwigs University of Freiburg, West German in 1967; and a doctoral degree in chemistry from the University of California, Berkeley, in 1972.

He was an author of the IPCC fourth assessment.