Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that well-arrayed and uniform-sized mesoscopic honeycomb morphology is formed in poly(styrene-alter-maleic anhydride) thin films spin-cast on glass slide substrate from tetrahydrofuran solution with the presence of hydrochloric acid and water. The phenomenon can be interpreted as the trace of water droplets emulsified by the hydrolyzed poly(styrene-alter-maleic anhydride) during the process of existence-evaporation transition, for which the hydrochloric acid is crucial. The self-assembling morphology may provide possibilities for further studies in the area of surface science and template fabrication. (C) 2000 Elsevier Science Ltd. All rights reserved.