James Baddiley was a biochemist who used the methods and insight of the organic chemist to answer important questions in biology, notably coenzyme structure and the structure and function of bacterial cell walls. A graduate of Manchester University, he moved to Cambridge in 1944 with A. R. Todd, where he synthesized adenosine triphosphate, the nucleotide concerned with essential energy transformations in all forms of life. As an independent researcher at the Lister Institute in London he elucidated the structure of coenzyme A and other coenzymes. He was appointed Professor of Organic Chemistry in Newcastle, where the exploration of the structures of two cytidine nucleotides led to the discovery of the teichoic acids, major components of the cell walls and membranes of Gram-positive bacteria. These discoveries were extended to cover the structures, biosynthesis, function and immunology of the teichoic acids. Baddiley became Professor of Chemical Microbiology in 1977. Moving to Cambridge after his retirement, he was able to continue his researches in the Department of Biochemistry. He was elected a Fellow of Pembroke College and as an elder statesman undertook extensive committee work, often as chairman, both in Cambridge University and nationally. He was knighted in 1977.