We herein report a dataset of 28 homolytic C–Cl bond dissociation energies (BDEs) (to be known as the CCl28 dataset), obtained using the benchmark-quality W1w thermochemical protocol. This set contains chlorinated organic molecules that consist of either sp3-, sp2- or sp-hybridized C–Cl bonds. The species in this set have C–Cl BDEs (at 298 K) that differ by as much as 168.4 kJ mol–1, with allyl chloride having the lowest BDE (291.7 kJ mol–1) and 1-chloroprop-1-yne having the largest (460.1 kJ mol–1). Given the benchmark quality of the CCl28 dataset, it may serve as a useful reference for assessing the performance of more approximate quantum chemical methods, such as density functional theory (DFT) and double-hybrid DFT methods.