The collapse of photoresist patterns in the production process is a problem stringently limiting the miniaturizing of microchips. Recently, it has been found that a cationic surfactant rinse has a positive effect on the pattern collapse. The present study investigates the adsorption of cationic surfactants onto photoresist surfaces. It has been found that the surfactant adsorbs both on unexposed and exposed photoresist. On exposed resist that is more hydrophilic and negatively charged than unexposed resist, a stronger adsorption was observed. Only on exposed resist the surfactant adsorption leads to a hydrophobizing that most probably accounts for the pattern collapse reduction.