Time-dependent adsorption of a high-molecular-weight cationic polyacrylamide (acrylamide/ beta -methacryloxyethyltrimethylammonium methyl sulfate copolymer) from sulfuric acid solution onto a perfluorosulfonate ionomer (Nafion) membrane was characterized using X-ray photoelectron spectroscopy (XPS), ultraviolet/visible spectroscopy (UV/vis), and dynamic contact angle measurements in water. Flourine and nitrogen atomic surface concentrations determined from XPS were well correlated to the adsorbed polymer surface coverage from water contact angle analysis via the Cassie relationship and the adsorbed polymer concentration from UV/vis, respectively. Cationic polyacrylamide surface coverage remained constant at about 60% for all immersion times investigated. On the other hand, the adsorbed polymer concentration increased with immersion time, approaching a plateau after about 9 min. Such behavior was attributed to the transition from an expanded, two-dimensional, adsorbed polymer chain configuration at early times to a three-dimensional configuration composed of either coils or multilayers as immersion time increased.