The paper describes a pyrolytic method of investigating the kinetics of gaseous reactions in which toluene is used as a carrier gas. It is shown that the method is particularly suitable for the determination of bond dissociation energies. The scope of the method is illustrated by various examples. A list of bond dissociation energies obtained is given. The manner in which the experimental results obtained can be cross-checked, is indicated and illustrated by examples. The effects of various constitutional factors on the bond dissociation energies are discussed.