We investigated the dynamics of the adsorption of O-2 on Ag(110) with the molecular beam technique combined with EEL spectroscopy and with the method of King and Wells. The initial sticking coefficient S-0 is reported for molecules impinging along both high symmetry azimuthal directions ([001]) and [1(1) over bar0$] as a function of total energy and angle of incidence of the molecules and crystal temperature. The initial sticking coefficient is anisotropic for low as well as for room temperature adsorption. The dependence of the sticking coefficient on the temperature of the sample, T-s, indicates that adsorption takes place directly into the molecular well. Dissociation is eventually induced thermally for T-s>150 K. The physisorbed state plays no role in the chemisorption process in the investigated impact energy range.