In this paper multifunctional aspects in operation of Pt/Rh/Ce/gamma-Al2O3 three-way catalyst (TWC) are discussed on the basis of computed spatiotemporal patterns of reacting and deposited species on specific active sites distributed in the catalytic washcoat layer. A spatially pseudo-one-dimensional, heterogeneous model of a TWC reactor has been developed, with well-mixed gas phase and description of diffusion in the porous catalytic washcoat. The model includes a detailed non-stationary kinetic scheme for CO and C2H2 oxidation, oxygen storage on CeO2, CO2 adsorption on the support and NOx transformation and reduction. Pt, Rh, Ce and gamma-Al2O3 sites are considered with different kinetic parameters. A methodology is developed for the studies of the effects of internal diffusion and washcoat composition (i.e. concentration and distribution of active Pt, Rh and Cc catalytic sites) on the conversion of main pollutants in automobile exhaust gas under transient conditions. Several cases of variable distribution of the catalytic sites in the washcoat layer are discussed with respect to the reactor performance. Effects of oscillations in the inlet oxygen concentration are studied. Complex interactions, particularly between reaction intermediates and the stored oxygen within the washcoat, cause the increase of conversions in the periodic operation when compared with the stationary one.