Preparation of honeycomb-patterned films from Poly (phthalazionone ether sulfone ketone) (PPESK), one of the thermally stable polymers, in a humid atmosphere was reported in this article. The mechanism of forming honeycomb structure was discussed. Some influences, such as the effect of PPESK concentration and the atmosphere humidity were tested. Furthermore, the thermal stability of honeycomb-patterned films was also investigated, and it was shown that the honeycomb structures could be stable existed at 300 degrees C. (C) 2008 Wiley Periodicals, Inc.