Polyvinyltoluene (PVT) latex particles were etched with O2 or CF4/O2 plasma and polystyrene (PS) latex by the O2 plasma. While the effect of these treatments on the surface topology and the specific surface area was minor, the electrokinetic measurements showed a significant change in the surface charge characteristics. The interpretation of the results in terms of a surface complexation model, taking the Stern–Gouy–Chapman structure of the interfacial layer into consideration, yielded the values of the corresponding equilibrium constants, which indicated that the chemical nature and the density of the surface charged groups were altered by plasma attacks.