Rate constants for induced decomposition of 5-hexenyl(1-hydroperoxy-1-methylethyl) diazene ((CH3)2C(OOH)N=N(CH2)4CH=CH2, 2) have been estimated. Thermolysis of 2 at 50 °C affords 5-hexenyl radicals which abstract the hydroxyl group from 2 in competition with cyclization of 5-hexenyl to cyclopentylmethyl radicals. The known rate constant (kc) for that cyclization was used to clock the bimolecular hydroxyl abstraction process. For reaction in hexafluorobenzene at 50 °C, the rate constant for abstraction of hydroxyl from 2 (kOH) was found to be dependent on the concentration of 2. For example, at [2] = 0.4 M, kOH = 3.2 × 106 M−1 s−1 whereas, at [2] = 0.10 M, kOH = 1.8 × 107 M−1 s−1. The concentration dependence of kOH is attributed to the effects of intermolecular hydrogen bonding and the large absolute values of kOH are ascribed to concerted induced decomposition, the O—O bond being broken in concert with scission of the nearest C—N bond of the azo function. The relevance of the results, to synthetic application of α-hydroperoxyalkyl diazenes in hydroxyalkylation reactions, is discussed.