Adsorption of human serum albumin (HSA) onto polypyrrole powder and polypyrrole-silica nanocomposite is investigated at pH 7.4 and RT using UV spectroscopy. the nanocomposite is more effective than the powder in adsorbing HSA (147 and 63 mg/g, respectively). XPS was used to detect characteristic features of the adsorbed HSA and to construct adsorption isotherms. These latter were in fair agreement with those obtained via UV. Polypyrrole-silica is adsorptive towards HSA at pH 7.4 by contrast with the quasi-zero adsorption previously obtained with the DNA adsorbate (Saoudi et al, 3. Colloid Interface Sci. 1997).