We have investigated the structures of CF3I, and its dissociation products, adsorbed on Ru(001) using low-energy electron diffraction and electron-stimulated desorption ion angular distribution (ESDIAD). Atomic iodine forms (√3x√3)R30° islands even at very low coverages. At 70% of saturation and above, a (2X2) superstructure forms which we attribute to a p(2X2) unit cell with one CF₃ group and one iodine atom. ESDIAD images show F+ desorbing at normal emission and in three hexagonal patterns. The normal emission is attributed to a tilted configuration of CF₃(ad) in which one C-F bond is oriented perpendicular to the surface. A small hexagon is attributed to F(ad) on step edges. A large hexagon at low coverages may arise from isolated CF₃(ad) species possessing C_3v symmetry. And finally, an intermediate hexagon is attributed to perturbation of the CF₃(ad) orientation by molecular fragments which result from electron irradiation of physisorbed CF₃I.