Cooking of agave is a basic operation in the production of mezcal in which the agave fructans are transformed into monosaccharides, and then these are converted to ethanol during fermentation. During these stages important minority compounds are generated such as the methanol, which is generated throughout the demethoxylation of the pectin in agave and that is toxic to humans, being strictly regulated in alcoholic beverages. This work evaluated the methanol production during the cooking of Agave angustifolia, from 92 to 122°C for 12 to 18 h. A first order kinetic model was developed, finding that the energies of activation of 90.64 and 115.96 kJ/mol for demethoxylation in stem and leaves, respectively. During cooking, the degree of demethoxylation of pectin reached 92%. It was estimated that most of the methanol produced was removed onto the water steam that was generated during cooking.