Single electron transfer (SET) processes – frequently utilized by Nature to activate its substrates – significantly enhance the reactivity of organic molecules. These SET reactions provide facile access neutral radicals – reactive intermediates that are particularly attractive for use in complex settings as a consequence of their general lack of reactivity with polar functional groups. The use of redox catalysis (e.g. photocatalysis and electrocatalysis) furthers the benefits of SET processes enabling the reduction of stoichiometric waste byproducts and toxic or hazardous reagents compared with classical approaches. The development of methodologies involving organic free radicals underpinned on practicality and mechanistic understanding with applications in biomass conversion will be presented.