Bondingness, originally used in a qualitative analysis of the barrier to rotation in ethane, has been used to model ΔfH° (g) for simple organic substances. The model is parameterised with a set of 345 molecules including alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, alkenoates, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. The model is compared with a current empirical scheme as well as a comparison of variations of the model using different simple steric potentials. Using bondingness and the most approximate quantum chemical models a model can be formulated that is comparable with empirical group methods but requiring less parameters.