Project Description. this work is focused on the study the adsorption of a strong polyelectrolyte Poly (sodium 4-styrenesulfonate) (PSS) at different pH values (3.8, 7.0 and 10.0) on neutral,positively and negatively charged surfaces. For this purpose, we use the quartz crystal microbalance technique, (QCM-D) that allows to quantifying the amounts of mass on a scale of nanograms (ng) in real time experiments. Our results show an adsorption on all cases previously described. In the case of neutral surfaces, we observe a sudden adsorption which decays with time. It is expected that the adsorption at equilibrium state will be lower. For the positive surfaces, the adsorption is higher when the polyelectrolyte is weakly charged; and it is low when the polyelectrolite is highly charged. And for the negative charged surfaces, the higher adsorption occurs at high pH values. This behavior could be associated to the interactions of co-ions of polyelectrolyte with the surface.