The kinetics of isomerization of C8‐aromatics on a bifunctional Pt/zeolite catalyst has been studied at 422°C, total pressures of 7.102 KPa to 18.102 KPa and H2/hydrocarbon ratios of 3 to 18 in a fixed bed reactor. The rate of ethyl‐benzene isomerization can be described on the basis of a bifunctional reaction mechanism. For modeling the rates of interconversion of the C8‐aromatics linear rate laws are suitable as long as hydrogen and hydrocarbon partial pressures are kept constant.