The catalytic cracking reaction pathways and mechanisms of 1-phenylhexane, 1-phenyloctane and 1-phenyldecane were studied. Experiments at 500 degrees C with a rare earth Y (REY) catalyst indicated that the dominant reactions included dealkylation and cracking in the alkyl side chain. To describe these results, a mechanistic model of the catalytic cracking of 1-phenyloctane was developed using a novel mechanism-based lumping scheme that exploits the chemical similarities within reaction families. The formal application of 17 reaction family matrices, which correspond to 15 reaction family classes, to the matrix representations of the reactants and derived products generated the model. The reaction family concept was further exploited to constrain the kinetics within each reaction family to follow a quantitative structure/reactivity Polanyi relationship. Ultimately, eight Polanyi relationship parameters, one catalyst specific parameter and three coking/deactivation parameters were optimized using experimental data. The resulting model correlations were excellent, as the overall parity between experimental and model values was y(Model)=0.00131+0.994y(Exp) with a correlation coefficient of 0.998.