Transparent, stable, electrically insulating, crystalline thin films of two aromatic organic dianhydrides, 3,4,9,10‐perylenetetracarboxylic dianhydride C24H8O6and 1,4,5,8‐naphthalenetetracarboxylic dianhydride C14H4O6, were prepared by vapor deposition. On exposure to an electron beam dose of 0.05 C cm−2the written areas of the films appeared visually blackened and were electrically conducting. This chemical transformation was found to be both dose and current density dependent. Fine lines with widths of 1000 A˚ were prepared by electron exposure at just above writing threshold doses. The chemical and electrical properties of the materials formed upone‐beam treatment were found to be notably different from those of the starting anhydrides and useful for semiconductor device fabrication.