Swedish Chemist Svante Arrhenius studied this phenomenon during the late 1880s, and stated the relations between reactive molecular encounters and rates of reactions (formulated in terms of activation energies).

In the 1950s, 1960s and 1970s, with the development of many sophisticated experimental techniques, it became possible to study the dynamics of elementary chemical reactions in the laboratory. Such as the analysis of the threshold operating conditions of a chemical laser or the spectra obtained using various linear or non-linear laser spectroscopic techniques.

In February 1967, he started working with Dudley Herschbach at Harvard University on reactions between hydrogen atoms and diatomic alkali molecules and the construction of a universal crossed molecular beams apparatus. After the postdoctoral year with Herschbach he joined the University of Chicago faculty in 1968. In 1974, he returned to Berkeley as professor of chemistry and principal investigator at the Lawrence Berkeley National Laboratory, becoming a U.S. citizen the same year. Lee is a University Professor Emeritus of the University of California system.

In addition to the Nobel Prize, his awards and distinctions include Sloan Fellow (1969); Fellow of American Academy of Arts and Sciences (1975); Fellow Am. Phys. Soc. (1976); Guggenheim Fellow (1977); Member National Academy of Sciences (1979); Member International Academy of Science, Member Academia Sinica (1980); E.O. Lawrence Award (1981); Miller Professor, Berkeley (1981); Fairchild Distinguished Scholar (1983); Harrison Howe Award (1983); Peter Debye Award (1986); National Medal of Science (1986). Yuan Tseh Lee was awarded the Othmer Gold Medal in 2008 in recognition of his outstanding contributions to progress in chemistry and science.

Lee played an important role during the 2000 Presidential Election and since then has been a supporter of the Pan-green coalition which advocates Taiwan independence. In the last week of the election he announced his support for the candidacy of Chen Shui-bian who subsequently won a narrow victory over James Soong. Chen intended to nominate Lee to become Premier, but Lee declined after a few days of deliberation. Lee has been the President of the Academia Sinica since 1994 and renounced his U.S. citizenship to take the post.

At the request of President Chen, Lee was the Republic of China's representative in the 2002 APEC leaders' summit in Mexico. (Presidents of the Republic of China have been barred from joining the APEC summits because of objections from the People's Republic of China.) Lee represented President Chen again in the 2003 and 2004 APEC summits in Thailand and Chile, respectively.

In 2003, he was one of 22 Nobel Laureates who signed the Humanist Manifesto.

In January 2004, he and industrial tycoon Wang Yung-ching and theatre Director Lin Hwai-min issued a joint statement asking both Chen Shui-bian and Lien Chan to "drop hatred and extreme behavior and resort to honesty." This, and other critical statements of the President, led to speculation that he would not back Chen again in the 2004 elections until he issued a statement of support for the DPP on March 17, 3 days before polls opened. He was elected President of the International Council for Science in 2008, to start his term in 2011.

In 2010, Lee said that global warming would be much more serious than Scientists previously thought, and that Taiwanese people needed to cut their per-capita carbon emissions from the current 12 tons per year to just three. This would take more than a few slogans, turning off the Lights for one hour, or cutting meat consumption, noting: "We will have to learn to live the simple lives of our ancestors." Without such efforts, he said, "Taiwanese will be unable to survive long into the future".

During the 2012 Republic of China Presidential elections, Lee expressed his support for DPP candidate Tsai Ing-Wen. In early 2016, he appeared and addressed a rally by New Power Party-a party formed by student Activists involved in the Sunflower Movement.

Yuan Lee has signed the 2015 Mainau Declaration expressing concern about anthropogenic climate change. (See Wikipedia's own article about the declaration.)

One of the major goals of chemistry is the study of material transformations where chemical kinetics plays an important role. Scientists during the 19th century stated macroscopic chemical processes consist of many elementary chemical reactions that are themselves simply a series of encounters between atomic or molecular species. In order to understand the time dependence of chemical reactions, chemical kineticists have traditionally focused on sorting out all of the elementary chemical reactions involved in a macroscopic chemical process and determining their respective rates.