The gas-phase thermal decomposition of cis-2-methylcyclopropane carboxylic acid was investigated in the temperature range 692-753 K and pressure between 10 and 70 Torr. Arrhenius parameters were determined for homogeneous, unimolecular formation of the isomeric products and for the overall loss-rate of the reactant. The determined values are in accordance with the Arrhenius parameters that were reported previously for the thermal unimolecular reactions of cyclopropane and other substituted cyclopropanes. The formation of isomeric products and the observed Arrhenius parameters are consistent with a biradical mechanism. The effect of surface on the reaction was studied at 732 K using the packed reaction vessel. It was observed that the rate of production of all isomeric products and the total loss of cis-2-methylcyclopropane carboxylic acid were not affected by increasing surface to volume ratio.