The modification of a HY zeolite (with Si/Al ratio = 2.5) by impregnation with a platinum salt or ion exchange with Cu2+ cations was carried out in order to evaluate the potential interest of the obtained materials as hydrocarbon traps for cold-start application. Textural, structural and chemical characterizations were carried out using N-2 adsorption isotherms at -196 degrees C, XRD and DRIFTS of adsorbed CO and NO. Acidic properties of the parent H/Y and Cu- and Pt-modified zeolites were determined using FTIR of adsorbed pyridine. The methodology used to investigate the adsorption behaviour of the parent and modified HY zeolites consisted in: (i) analysing qualitatively and quantitatively the breakthrough curves obtained at 35 degrees C during the adsorption of a ternary hydrocarbon mixture (propene, toluene, decane) as well as the data from subsequent temperature-programmed experiments (TPD under He or TPSR in presence of 10%O-2 or 10%O-2/0.2%NO) (ii) establishing relationships between adsorption/reactivity data and the structural, textural and chemical properties of the modified zeolites. Namely, the introduction of copper and platinum species considerably improves the adsorption of unsaturated hydrocarbons, such as propene or toluene, at the expense of decane. This results in a more adequate balance between all the hydrocarbons adsorbed, which is required for cold-start application. In addition, Cu/Y and Pt/Y zeolites were also found to be efficient for the removal of NOx or HC total oxidation, respectively.