Ab initio and DFT calculations reveal that intermolecular radical additions of both acyl and oxyacyl radials to hydrazones occur through SOMO → π*_hydrazone, π_hydrazone → SOMO and LP_N → SOMO interactions between the radical and the hydrazone π-system. Both acetyl and methoxycarbonyl radicals show preference for addition to the carbon end of the carbon–nitrogen π-bond. At the highest level of theory used in this study (G2//MP2(full)/6-31G*), energy barriers of 11.2 and 22.6 kJ mol^–1 are calculated for acetyl radical addition to the carbon and nitrogen-ends of N-aminomethanimine respectively. The analogous energy barriers for the methoxycarbonyl radical are 4.9 and 25.7 kJ mol^–1 at the same level of theory.