Hush has contributed to chemical physics and theoretical chemistry. His Theory of homogenous and heterogenous electron transfer as a thermal rate process has become generally accepted. Later he identified a radiative process in electron transfer, and investigated a number of key examples. His theoretical work has been in the use of self-consistent field molecular orbital theory in electron transfer problems, particularily in the electron transfer systems of certain tetrapyrrole macrocyclics and their metal complexes. The combination of ingenious experimentation and convincing theoretical interpretation is a feature of his work, which has been notably original, and is in areas of real importance.