Applying laser heating by fast vibrational–translational energy transfer in a quasi-wall-free reactor the pyrolysis of ethyne (C₂H₂), propyne (p-C₃H₄), and propadiene (a-C₃H₄) was studied experimentally at 0.13 bar in the medium temperature range of 800–950 K with respect to the degradation and formation of hydrocarbons. The radical/hydrocarbon chemistry was chemically induced via CH₃ radicals produced by the fast thermal dissociation of di-tert-butyl-peroxide DTBP ((tert-C₄H₉O)₂ → 2 CH₃ + 2 CH₃COCH₃). Complete analysis of the product yields was achieved by means of GC-MS with special attention to isomeric product and benzene formation. The product distribution, the temperature dependence and the underlying reaction schemes were analyzed by kinetic models developed for high temperature alkane oxidation/pyrolysis and aromatic formation in premixed ethene and ethyne flames. The primary attack of the unsaturated hydrocarbons by CH₃ radicals in the studied temperature range occurs via the addition to the double/triple bond and via hydrogen atom abstraction, leading to different classes of radicals. For the reaction system C₂H₂ + CH₃ high yields of C₆H₆ with a marked negative temperature dependence were observed. A semi-quantitative description of the C₆H₆ yield was obtained by a reaction sequence of successive addition of C₂H₂ to the radicals C₂H₃ (from C₂H₂ + H) and C₄H₅, being consistent with recent discussed reaction networks. For the reaction systems p-C₃H₄ + CH₃ and a-C₃H₄ + CH₃ only qualitative agreement between measured and modelled product yields was found, pointing to a lack of reliable data of the reactions of p-C₃H₄/a-C₃H₄/C₃H₃/H. Modified mechanisms are presented for the radical rich reaction systems C₂H₂ + CH₃, p-C₃H₄ + CH₃, and a-C₃H₄ + CH₃ experimentally studied.