The adsorption and zeta potential of three different alkyltrimethylammonium bromides, CTAB, TTAB, and DTAB, and two alkylpyridinium chlorides, CPC and DPC, on a PTFE surface were studied. Adsorption isotherms having characteristics similar to those of two plateau regions were observed for all these surfactants. In the case of alkyltrimethylammonium bromide, there is a considerable effect of chain length which could be attributed to the arrangement of surfactant molecules being tilted away from the perpendicular. In the case of alkylpyridinium surfactants, an insignificant effect of chain length is due to a predominantly perpendicular arrangement. The thermodynamics of hemimicellization has been described by evaluating nh, as well as free energy of hemimicellization.