Densely packed amino-terminated monolayers of high degree of order were formed by self-assembly of amino-terminated alkanethiols. Negatively charged poly(styrenesulfonate) (PSS) molecules were electrostatically adsorbed on the NH3+ surface. The density of single PSS molecules on the surface was regulated by carefully controlling its concentration as well as adjusting the time in the dilute solution. Dynamic force microscopy in "tapping mode" was applied to map PSS polymers with molecular resolution. The lateral dimensions (15-25 nm) and heights (0.5-1.0 nm) of the adsorbed PSS macromolecules are in fair agreement with the theoretical diameters and the experimental estimations. The average area, volume, and charge density of single PSS patches absorbed on a positively charged surface is 378 nm(2), 122 nm(3), and 0.90e(-)/nm(2), respectively. The structure of adsorbed PSS polymers was discussed down to the molecular scale. The observations support the patch charge model of flocculants.