In the current research, a highly controllable system operating at low temperatures and for short reaction times is employed for the surface sulfonation of low-density polyethylene. This system provides the advantages of short reaction times and low reaction temperatures, as compared with previous methods of surface sulfonation. Low-density polyethylene films were sulfonated at 40 degrees C for time periods ranging from 5 to 30 min. Subsequently, all films were analyzed by SEM, EDX, horizontal ATR-FTIR, surface roughness, and dynamic contact-angle measurements. Sulfonation was effected at all reaction times. The degree of surface sulfonation increased through 10 min and reached a maximum between 10- and 30-min reaction times with concomitant changes in the physicochemical properties of the material. At 30 min, the film topography changed substantially, indicating that sulfonation was no longer limited to a strictly surface reaction.