The interaction of Li with Ru was investigated on Ru(001) and Ru(109) using work function measurement, temperature-programmed desorption and low-energy electron diffraction. Strong depolarization effects for Li atoms at atomic step sites are observed, causing the dipole moment of a chemisorbed Li atom at the limit of zero coverage to decrease from 10 D to 6 D. In contrast to the (n x n) incommensurate Li structures observed on Ru(001), the Ru(109) surface does not produce any ordered Li structures. Despite these differences, the thermal desorption kinetics for Li from Ru(001) is virtually identical to that from Ru(109) at all coverages. (c) 2006 Elsevier B.V. All rights reserved.