Catalysis underpins the sustainable future of chemistry as the single most broadly applicable tool to reduce the energy and material requirements of chemical synthesis across all scales. Understanding catalytic processes is therefore key to development and application of all catalytic systems. Although great strides have been made in this regard, hidden catalysis still plagues new chemical reactivity and synthetic methodology. Hidden catalysis (Scheme 1A) has been identified across all areas of synthesis from cross-coupling reactions to the functionalisation of unsaturated bonds. Notable examples include trace metal contaminants accounting for the perceived reactivity of iron salts, 'metal free' cross-coupling reactions, Brønsted acid catalysis being responsible for (formal) hydrofunctionalisation reactions, and dioxaborolane decomposition products accounting for catalytic activity and low regioselectivity. Identifying hidden catalysis is non-trivial (Scheme 1B) and therefore easily missed as optimisatin is routinely focussed on high catalyst activity. In-depth, time-consuming mechanistic analyses are required; for example ICP-MS analyses of reagents and reaction mixture are needed to identify trace metal contaminants followed by reaction profiling to determine the kinetic viability of each of the identified trace metals at the measured level and finally determination of each components catalytic potential. Hidden Brønsted acid catalysis can be even more difficult to identify as complex acids, not simple mineral acids, are often responsible for reactivity and kinetic analyses can result in inconclusive results. The catalysed hydroboration reaction has become a go-to as a testbed of catalytic activity for species from across the periodic table, with over 600 publications on catalysed hydroboration reactions using HBpin since 2010 alone. The state-of-the-art method to distinguish between 'hidden' and 'true' catalysis relies on the trapping and in situ characterization of boranes, particularly BH3, generated under catalysis conditions using N,N,N',N'-tetramethylethylenediamine (TMEDA) and B NMR spectroscopy (Scheme 1C), The H3B•TMEDA complex can be observed by B NMR spectroscopy, even following aqueous work-up, and quantitative assessment was possible by comparison of rates of reaction. More commonly the addition of TMEDA to inhibit hydroboration catalysis in situ has been used (see Supporting Information, S6). Prior to the introduction of this method, only 5% of publications tested for hidden borane catalysis. Following the introduction of the TMEDA tests, 23% tested for hidden borane catalysis, but 58% of these were carried out above 60 °C, where the H3B•TMEDA adduct is highly labile so the test invalid. Thus, uptake remains low, application inappropriate and a simple method for the identification of hidden borane catalysis remains elusive.