The composition and structure of the Cu85Pd15(110)-(2×1) surface has been determined by low-energy ion scattering. From time-of-f forward scattering and recoiling measurements it is concluded that the surface is unreconstructed. The equilibrium composition of the first two atomic layers is determined by comparing the energy and azimuthal distribution of backscattered 2 keV Ne+ ions as obtained with the EARISS (energy and angle-resolved ion scattering spectrometer) with three-dimensional ion trajectory simulations. For the first layer, a slight depletion in Pd is found (11±2 at%), whereas the second layer is strongly enriched in Pd (40±8 at%). These results are in reasonable agreement with an earlier proposed model [D.J. Holmes, D.A. King and C.J. Barnes, Surf. Sci. 227 (1990) 179]. In addition, the thermal segregation after sputtering at room temperature was investigated which showed similar behavior as was recently reported on Pt10Ni90(110) [P. Weigand, B. Jelinek, W. Hofer and P. Varga, Surf. Sci. 295 (1993) 57].