Temperature-programmed dynamic Monte Carlo simulations describe the time evolution of adsorption and desorption of molecular oxygen, its dissociation, and atomic oxygen diffusion. A hexagonal lattice containing six adsorption sites per unit cell represents the Pt(1 1 1) surface. The temperature is increased linearly with time, starting with an empty initial surface. Temperature effects on the rate of molecular oxygen adsorption are incorporated through the temperature dependence of the O-2 sticking coefficient and that of the flux of molecules impinging the surface at a given pressure. The results illustrate the mechanisms by which molecular oxygen cannot be adsorbed at temperatures above 155 K. (C) 2003 Elsevier B.V. All rights reserved.