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 [7]). 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 (Delta H-298(double dagger) = 40.6 and 39.5 kJ mol(-1), respectively). (C) 2013 Elsevier B.V. All rights reserved.