Historically, the first in-depth mechanistic discussion of the HOR/HER reactions in combination with the B-V model, appearing there in its current form for the first time, is the 1930 publication by Erdey-Grúz and Volmer , although the authors did not refer to the possible elementary steps (Eq 27) with the names known today. The Tafel step predates from Tafel's noteworthy publication in 1905 referenced by Erdey-Grúz and Volmer , who introduced the Tafel equation in their study of the HOR/HER mechanism. The first record of the Volmer step, written as we know it today, in the context of the HER is found in the dissertation by Heyrovský in 1916 , where he studied effects from oxide formation on aluminum amalgams on the HER and put forward the idea of recombination of negative and positive hydrogen ions as its mechanism on all metals. This idea, which was mentioned again in 1927 , has been referenced in the electrochemical literature as the introduction of the Heyrovský step . However, it appears that this is a mistake as Heyrovský wrote H -as H', easily mistaken as an adsorbed hydrogen atom given today's nomenclature of * H. Instead, Heyrovský refers to Richards and Tanaka about the step that now bears his name to gain insight into the energies of his proposed union of H -and H + . This step was then employed by Erdey-Grúz and Volmer , albeit split as three steps using an intermediate H 2 + , as their proposed mechanism of the HOR/HER on metals. In 1937 Frumkin provides an overview over the various proposed HER paths , where Heyrovský's suggestion of the "ionic union" is described to be equivalent to descriptions of the contemporary Heyrovský step by other authors, ultimately leading to its name. Frumkin also made the important remark, that the zeta-potential (energy difference of species in the electrode's double layer and the bulk of the solution) is assumed to be zero, an assumption that is made implicitly in nearly every mechanistic discussion to this date, including this work, albeit not knowing the extent of the resulting error. Today, these steps are introduced into mechanistic discussions as "generally accepted" , more as a convenience rather than from an abundance of scientific evidence. Following this tradition, we employ these steps to perform a detailed kinetic and experimental analysis of the HOR/HER on polycrystalline Pt, in the hope that we can thereby contribute to the long debate , , on whether the HOR/HER on Pt proceeds via the Tafel-Volmer, Heyrovský-Volmer or a combination of both paths, which step is rate-determining, and whether it changes at different potentials, pH ranges, and type of electrolyte ions. We investigate how varying reactant activities and electrolyte ions affect the HOR/HER kinetics in as broad a range as possible, and revisiting mass transport corrections in the micropolarization region. Furthermore, we extend this comprehensive experimental and microkinetic campaign to the analysis of the H-upd region in a quest towards a cohesive picture of the HOR/HER and H-upd kinetics. In this journey we acknowledge that the Butler-Volmer relationship itself originates from observations of the HOR/HER kinetics during the 1920s. Consequently, discussions of the HOR/HER through the Butler-Volmer relationship are somewhat self-referencing. Despite substantial progress by Marcus and others, we are not yet in possession of a and scientific theory of electrochemical kinetics.