Abstract Electronic overlap population is explored as a reactivity measure for several bond cleavage and bond formation processes. The reactions considered include: I. decarboxylation of carboxylic acids and of their anions; II. carbon-hydrogen bond cleavage in γ-radiolysis of glutaric, methyl-malonic and 3-hexendioic acids; and, III. hydrogen atom addition to butadiene and to sorbic acid.