Adsorption measurements of the adhesive protein isolated from the blue mussel Mytilus edulis L onto type 304L stainless steel were performed. The adhesive protein is a high-molecular-weight biopolymer (100 kDa) that contains catecholic functionalities, which in principle are excellent iron chelators. From these measurements, adsorption isotherms were determined, and the maximum number of binding sites/m(2) and the affinity constant were calculated. These values were compared to those measured for three other adsorbates onto type 304L stainless steel, namely, bovine serum albumin (BSA), L-3,4 dihydroxybenzoic acid (DHBA), and poly-L-lysine. Studies indicate that the mussel protein exhibits the highest affinity constant for the stainless steel of all the adsorbates and multilayer adsorption occurs at the mussel protein:metal interface; the other adsorbates exhibit Langmuir-type monolayer adsorption. The mussel protein significantly inhibits dissolution of iron and chromium metal from the stainless steel at pH 7.8, whereas the other adsorbates enhance it. These results indicate that the mussel protein forms a stable metal-protein complex at the surface of the metal that does not desorb into solution.