Physical chemistry – the study of the interplay between structure and reactivity in organic molecules – underpins chemistry, and that we cannot imagine chemistry as a subject matter without knowledge of mechanism and reactivity. it's sometimes thought that the golden age of ‘physical organic chemistry’ was within the 20th century, when systematic information about mechanism first burst onto the scene. Certainly the impact of early knowledge of mechanism of fundamental aliphatic substitution reactions, among others, was enormous, but our knowledge of reactivity and mechanism has continued to progress and deepen enormously ever since and this has been reflected in a very number of Nobel Prizes in Chemistry. In a region of particular interest to me, the transformation of radical chemistry from being an almost impenetrable area to 1 that may be usefully harnessed even in synthetic applications, has been extraordinary – this transformation has been relatively recent and has been principally obsessed with the accurate determination of kinetics of radical reactions. Applications to complex reactions in biology, polymer chemistry and electronic materials are ever more prevalent, and boost contributions in ‘small molecule’ chemistry. Novel experimental techniques combined with the revolution in computational chemistry give new impetus to physical chemistry and contribute to its continuing importance, an importance that's reflected within the sizable amount of international meetings in physical chemistry within the past two years.