Catalytic cracking of octanoic acid was studied previously in our laboratory [J. Anal. Appl. Pyrolysis 58/59 (2001) 605]. The mechanism proposed by Leung et al. [Energy Fuel 9 (1995) 913] for carboxylic acids was checked and well validated by this parametric study with activated alumina (ALCAN) as catalyst. So, a kinetic study of catalytic cracking of octanoic acid was realized to determine the reaction order and the kinetic parameters. The experiments were carried on in changing the catalyst mass and the temperature (low values for obtaining low conversions). The aim of this study was to complete better the mechanism of catalytic cracking of fatty acids and to use it in the future for the catalytic cracking of oleic acid issued from vegetables oils.