The thermal decomposition of 2,4-dimethylpyrrole was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 1050-1250 K at overall densities of similar to3 x 10(-5) mol/cm(3). A plethora of decomposition products, both with and without nitrogen, were found in the post-shock mixtures. They were, among the nitrogen containing products: pyridine, two isomers of methylpyrrole, 2-picoline, 5-picoline, HCN, CH3CN, C2H3CN, C2H5CN, and CHdropC-CN. Very small quantities of cis- and trans-CH3CH=CHCN and CH2=CHCH2CN were also found in the post-shock mixtures. Among the products without nitrogen were CH4, C2H4, C2H6, C2H2, CH(3)CdropCH, CH2=C=CH2, C4H4 and C4H2, and very small quantities of other C-4 hydrocarbons and C-5 hydrocarbons. The initiation of a chain mechanism in the decomposition of 2,4-dimethylpyrrole takes place via ejection of hydrogen atoms from spa carbons and dissociation of the two methyl groups attached to the ring. The H atoms and the methyl radicals initiate a chain mechanism by abstraction of a hydrogen atom from the methyl group and by dissociative recombination of an H atom and removal of a methyl group from the ring. In addition to the dissociation reactions, there are several unimolecular channels that involve ring cleavage. Ring expansion processes that lead to the production of high yields of pyridine and picoline take place from radical species: CH3[C4H2NH]CH2. in the production of picoline and [C4H3NH]CH2. in the production of pyridine. In addition to the chain mechanism, there are unimolecular breakdown processes of the pyrrole ring to yield stable products such as HCN, CH3CN, and others. The total decomposition of 2,4-dimethylpyrrole in terms of a first-order rate constant is given by k(total) = 10(16.31) exp(-75.7 x 10(3)/RT) s(-1). A reaction scheme containing 36 species and 69 elementary reactions was composed and a computer simulation was performed over the temperature range 1050-1250 K at 25 K intervals. The agreement between the experimental results and the model prediction for most of the species is satisfactory.