Atomic modeling was conducted to investigate the origin of S interactions with Pd alloy H selective membrane candidates selected from the Pd-Cu, Pd-Ag, and Pd-Au binary systems, as well as their constitutive metals. The electronic characteristics of these alloy/metal systems played a more predominant role in controlling S bonding behavior than surface site geometries. The electronic coupling of S p orbitals bonding with alloy/metal d-bands in the adsorbate/slab density of states split the lower energy p bonding state and the d-band center further apart with increasing S bonding strength. A universal linear correlation was established for increasing adsorption strength (decreasing adsorption enthalpy) of 0.25 monolayer S with the increasing density of states energy difference: [d-band center - S p bonding peak]. The S interactions predicted at higher coverage provided indications of alloy susceptibility to irreversible S corrosion. The reversible adsorption of 1.0 monolayer S was only the most stable configuration on the more open Pd(0.5)Cu(0.5) Im (3) over barm and P(4)mmm (1 1 0) surfaces. The most competitive configuration for the interaction of a full S monolayer with the Pd(0.75)Cu(0.25) Pm (3) over barm and Pd(0.875)Au(0.125) Fm (3) over barm surfaces was the partial desorption and coupling of S. Partial incorporation of S to form a mixed absorbed/adsorbed S monolayer was more favorable for the Pd Fm (3) over barm (1 1 1) surface, and also on the Pd(0.5)Cl(0.5) P(4)mmm (1 0 1) and Pd(0.75)Ag(0.25) Pm (3) over barm (1 1 1) surfaces when accompanied by Pd segregation. The combination of S incorporation and Pd segregation was interpreted to be the first step towards nucleation of irreversible Pd(4)S formation. (C) 2011 Susanne M. Opalka. Published by Elsevier B.V. All rights reserved.