The thermal reaction of ozone with trimethyl aluminum was explored using twin jet, concentric jet, and merged jet deposition into cryogenic matrixes. Infrared spectroscopy and density functional theory calculations were employed to identify and characterize the products formed in each case. Together, these deposition techniques provide information over the essentially full course of the gas-phase reaction. At short times with twin jet deposition, the primary product is the O atom insertion product (CH3)(2)AlOCH3. With merged jet deposition and longer gas-phase Mixing times, the methyl peroxy radical H3COO center dot was seen in good yield,along with final stable products H2CO, H3COH, and C2H6. Production of Al2O3 and its deposition onto the walls of the reaction tube as a powdery film was noted as well. All of these outcomes were combined to propose a reaction mechanism for this system. Of particular note, the observation of H3COO center dot provides clear evidence for a free radical component to the overall mechanism.