Free radicals contain an unpaired electron and as such are often highly reactive species that are utilised in many chemical and enzymatic reactions, and can also participate in a wide range of unwanted processes such as the degradation of materials and oxidative damage to peptides. Our group is part of the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, and we have been working with other Centre members to study both fundamental aspects of radical reactivity and applications in chemical synthesis and biological processes. One of our current interests are nitroxide radicals, which are stable free-radicals capable of acting as antioxidants in biological systems and materials, and as control agents in free-radical polymerisation. We have recently studied the effects of substituents on their electrochemistry and radical trapping abilities, and are working with Professor Bottle (Queensland University of Technology) to use this information to identify structural improvements. We are also working with synthetic chemists to find new and improved tin-free chain carriers for organic synthesis. With Professor Zard (Ecole Polytechnique) we have been studying the kinetics and thermodynamics of reactions mediated by xanthic anhydrides, while with Associate Professor Sherburn we have been investigating tris(trimethylsilylmethane) and derivatives of ethyl piperidinium hypophosphate. We have also been working with a team led by Professors Radom and Easton to study hydrogen atom transfer in peptide radicals, and also in coenzyme B-12 mediated reactions.