Ar and CO2 physisorption on a very well crystallized sample of fullerene C-60 was studied by means of Monte Carlo computer simulations. Ar and CO2 experimental isotherms were determined on high-purity C60 to fit the potential parameters. Analysis of the structure of the adsorbed film indicated that both gases are adsorbed in the voids of the C-60 structure in a solid state with densities slightly larger than the bulk solid. Both gases exhibited a behavior similar to nitrogen. The cross-sectional area found for Ar is 0.121 nm(2). The existence of three adsorption sites found previously has been confirmed.