The Department of Chemistry was saddened to note the passing of Professor Thomas T. Tidwell, on December 29, 2025, in Sun City Center, Florida.
“Tom moved to Toronto in 1972 and continued teaching and supervising students until his retirement in 2005,” said Department Chair Mark Lautens. Tidwell was a faculty member at UTSC, he said, though his labs were on the St George Campus.
An obituary in The Globe and Mail reports that Tidwell (1939-2025) spent most of his career working at the University of Toronto as Professor of Chemistry, including a stint as Acting Dean of Scarborough College. He was described as an active mentor and collaborator with over 300 publications. He was a particular expert on the chemistry of ketenes, highly reactive organic compounds that react readily with compounds containing active hydrogen, like water or alcohols.
Lautens noted that Tidwell remained active in publishing and was still writing about the history of physical organic chemistry even a few years ago.
Professor Mitch Winnik of the Department of Chemistry said Tidwell joined U of T in part because of strongly held political beliefs and opposition to American interventionism in countries like Vietnam. He was a valued member of the faculty, he added. “He was full of good ideas and was always willing to talk,” said Winnik.
In an interview with the department newsletter, Distillations, on the occasion of his retirement, Tidwell spoke of keeping things simple as an educator. “What a teacher is supposed to do is to encourage students to do better and to think that they can do better.”
"I try to convince all the students, the best and the weakest, that chemistry is interesting, and not too difficult.”
The Department of Chemistry extends its condolences to Tidwell’s family and friends and remembers him as a dedicated scholar, mentor, and colleague whose influence continues to resonate.
