We present a generalized crossover (GC) model for the excess adsorption of pure fluids at a flat solid-liquid interface, which reproduces scaling behavior of the excess adsorption in the critical region and is reduced to the classical, van der Waals-type analytical model far away from the bulk critical point. In developing this model, we used the density-functional theory (DFT) approach for the order parameter profile calculations with a generalized corresponding states model for the local free-energy density. The GC DFT model well represents the available experimental adsorption data for Kr/graphite, C2H4/graphite, C3H8/graphite, CO2/silica, and SF6/graphite systems in the entire density range 0<ρ,&LE;3ρ(c) and temperatures up to 1.7T(c). In the critical region 0.5ρ(c)0, within experimental accuracy. At Lmuch greater thanxi(b) (where xi(b) is a bulk correlation length) the SCD model is transformed into the GC DFT model for semi-infinite systems. Application of the SCD model to the excess adsorption of carbon dioxide on the silica gel is also discussed. 0 2004 American Institute of Physics.