Exhaust gas temperatures of automotive gasoline engines are not high enough for 3-way-catalyst to activate at the engine cold start conditions. As the results, unburned hydrocarbons of high concentration are emitted to the atmosphere without being oxidized. This study was conducted to investigate the characteristics of HC adsorber using zeolite to store HC just after cold start condition and purify later when gas temperature rises. Experiments using model gas test apparatus, engine bench test stand and chassis dynamometer were performed to examine the adsorption and desorption performance of adsorber substrate. The effects on the performance of ion exchanging with zeolite, the species of zeolites, the silica alumina ratio, binder species inside the coated layer in the honeycomb substrate were measured. The influence of the volume of the adsorber substrate and the thermal durability were also investigated.