Investiuations of multiple-component isothermal adsorption dynamics are indispensable to a better understanding of the performance of automobile exhaust gas cleaning systems particularly in the stage of cold start. Dual-component adsorption isotherm equilibrium and dynamics at 323.15 K were explored experimentally in this study. A ZSM5-coated (Si/Al = 150) monolithic hydrocarbon absorber (ADS #1) and a monolithic light-off catalyst (CAT #1) were used as the model adsorbents. 2,2,4-Trimethylpentane (TMP) and toluene were chosen as the model gasoline constituents. In the dual-component system of TMP and toluene, TMP emitted earlier than toluene under the typical conditions where both are relatively comparable in the molar fractions in the gas phase. However, the reversed breakthrough occurred under the conditions where toluene was predominant over TMP in the molar fraction in the gas phase. (c) 2007 Elsevier B.V. All rights reserved.