The vinyl alcohol-acetaldehyde tautomerization reaction has recently received considerable attention as a potential route for the formation of organic acids in the troposphere (Andrews et al., 2012 ). We examine the catalytic effect of inorganic acids in the troposphere (e.g. HNO3, H2SO4 and HClO4) on the vinyl alcohol-acetaldehyde tautomerization reaction, by means high-level thermochemical procedures. We show that H2SO4 and HClO4 catalysts lead to near-zero reaction barrier heights for the vinyl alcohol → acetaldehyde reaction, and to low reaction barrier heights in the reverse direction (ΔH298‡=40.6and39.5kJmol-1, respectively). © 2013 Elsevier B.V. All rights reserved.