He continued as a post-doctoral fellow at L'Université Louis Pasteur, and worked in Kyoto, Japan before becoming an assistant professor of chemistry at The University of Texas at Austin in 1984.

Discussions with his colleagues regarding possible treatments eventually led to the discovery of so-called "texaphyrin" molecules, named as such due a semblance to the shape of the five-pointed star in the State flag of Texas.

[1],10-Gallon Molecule Stomps Tumors In 1996, Sessler described possible uses of these compounds in medicine in the Proceedings of the National Academy of Sciences journal.

Sessler has participated in hosting chemistry circuses on the UT campus.University Events | What Starts Here Changes the World, UT DISCOVERY MAGAZINE v15n4 Science Fun Day photo These circuses are held for different grade levels from elementary to college, and aim to expose students to "fun" aspects of chemistry.

Sessler has also lectured on how the disease Porphyria, caused by a deficiency in porphyrins, may be related to the origin of myths about vampires and werewolves.