(HAT) chemistry. Such insights have led to the discovery of unique selectivity for known transformations along with the development of new chemical reactivity. HAT, the concerted migration of a proton and an electron from a TM-H bond to an acceptor molecule, has emerged as one of the most useful chemical processes for the hydrofunctionalization of alkenes. In its most common manifestation, the generation of a TMH involves the exposure of an appropriate metal complex to a stoichiometric amount of reductant, such as a silane. Its subsequent interaction with an olefin leads to the formation of a C-H bond at the less electronically stabilized position along with a carbon-centred radical on the adjacent position. This intermediate can then be trapped with various agents to form new C-C, C-N, C-O, and C-X bonds. While the overall process formally requires only the addition of a single proton and an electron to form the active TMH catalytic species, exogenous chemical oxidants, such as peroxides and N-fluoropyridinium salts, are often required to illicit this reactivity. The application of HAT chemistry on a large scale could be problematic due to the need for an excess amount of external reductants with or without peroxide additives, resulting in poor atom economy and scalability concerns (Figure ). Given the growing documented utility of such reactions in organic synthesis, it is clear that more practical and universal variants are needed. In parallel, the same types of species have been efficiently and sustainably generated in the hydrogen production field with a proton as the hydride source (Figure ). For example, hydrogen evolution via electrochemically generated Co-H species was known as early as 1985. The field was dormant for over two decades until recently, with interest in cobalt-catalyzed electrochemical hydrogen evolution for green energy storage being the subject of a large body of studies spanning hundreds of publications. These robust Co-H based processes feature high turnover numbers and have been optimized to high levels with >90% efficiency of H2 production from simple protic systems suggesting their commercial implementation is immanent. From a mechanistic standpoint, Co-H is formed in-situ by the protonation of low valent Co(I)/Co(0) intermediates after direct cathodic reduction. Subsequently, it can react via two different pathways to form hydrogen and regenerate the cobalt catalyst. In the first suggested mechanism, the generated Co(II)-H species decomposes by proton attack and evolves hydrogen via an intermediate dihydrogen metal complex. Alternatively, Co(III)-H can be reduced to Co(II)-H which is followed by a similar protonation step. Interestingly, the described process operates with high faradaic efficiency in aqueous or non-aqueous mediums and various types of proton sources, such as water, TFA, TsOH, and alcohols. Amongst the many cobalt complexes enlisted, many do not require complex ligand architectures with simple bipyridyl or porphyrins derivatives performing robustly. Inspired by the well-established Co-electrocatalytic hydrogen evolution chemistry precedent outlined above, disclosed herein (Figure ) is a set of chemoselective, tunable electrochemical HAT (e-HAT) protocols free of chemical reductants and oxidants (e.g. silanes, peroxides) or rigorous experimental protocols (moisture tolerant, no glove-box). Thus, a versatile range of tunable reactivities with alkenes and alkynes-such as isomerization, selective reduction, and hydrofunctionalization (Figure )-can be realized with unmatched efficiency and chemoselectivity beyond that observed under purely chemical conditions. In support of these claims, this electrochemically-enabled reactivity is benchmarked with several of the most popular and recently disclosed chemical methods. Additionally, in-depth mechanistic analysis using cyclic voltammetry, UV-VIS spectroelectrochemistry, computation, and kinetics provides insight into e-HAT and rationalizes the observed selectivity. Finally, the scalability of this process is demonstrated in both batch and flow [gram-centigram (0.05-0.8 mole) scale].