Molecules extracted from biomass can be complex, and computing their reactivity on a catalyst is a real challenge for theoretical chemistry. We present herein a method to predict polyalcohol reactivity in heterogeneous catalysis. We start from a set of simple alcohol molecules, and we show that an accurate linear energy relationship can be constructed from DFT calculations for the O–H and C–H dehydrogenation reactions. We then show that this relation can then be used for a fast prediction of the reactivity of glycerol. Compared with pure DFT calculations, our method provides results of good accuracy with a systematic deviation of ∼0.1 eV. We were able to prove that this deviation is caused mainly by intramolecular effects occurring in glycerol and not in simpler molecules.