Professor Larsen has made an outstanding contribution to the chemical sciences in New Zealand over the past 30 years. In that time, he has published 105 papers and is a named inventor on five different patent families. He has been actively engaged in several areas of organic chemistry, from natural products synthesis, through medicinal and biological chemistry, and to drug development. His more recent work on carbon monoxide releasing molecules has had a significant impact on the field. The IP has been protected and the technology is being assessed for use as a protective agent in organ transplants, demonstrating his influence outside of the traditional organic chemistry field. His impact on the chemical sciences in teaching, mentoring and leadership is also noteworthy. Professor Larsen has imparted his wealth of knowledge on generations of young scientists, work colleagues and collaborators at the University of Otago and further abroad.