AbstractThe decomposition rate constant of i‐PrI under conditions of very low‐pressure pyrolysis (VLPP) is completely consistent with the well‐known high‐pressure Arrhenius parameters and the RRK(M) theory. The decomposition of n‐PrI under the same conditions proceeds via two pathways, the anti‐Markownikoff dehydroiodination and CI bond scission. The data, analyzed by taking into account the mutual interaction of the two pathways, is completely consistent with the known Arrhenius parameters for the bond scission step and, when combined with a reasonable A‐factor, yields an activation energy for HI elimination which is as predicted for these semi‐ion pair transition states.