Plasma protein adsorption-desorption kinetics on glutathione (GSH) and L-cysteine (L-cys) immobilized on gold was studied, using in situ ellipsometry, After immobilization, the adsorption-desorption kinetics in phosphate buffered saline (PBS) and Hank’s buffers were monitored for the two surfaces, with gold as a reference, Significant differences in the adsorbed amounts and the individual kinetics for the three surfaces were observed, The glutathione-modified surface was, with respect to protein adsorption, the most sensitive to the presence of calcium in buffer, The adsorbed plasma proteins could, to varying degree, be removed by altering the ionic composition of the surrounding buffer.