To examine the possibility of applying the iodination of nylon 6 to forming, a new type of nylon 6-iodine complex films iodinated before forming (IBF film) and the old type of films iodinated after forming (IAF film) were prepared and their structures were investigated and compared with each other. The IBF films from iodinated nylon 6 powders could be obtained by a melt press at 185degreesC, which is much lower than the melt-press temperature of pure nylon 6 (250degreesC). It was ascertained that the structure of IAF films is similar to that reported by Lee et al. but the structure of IBF films is very different. The distinctive features of the IBF films compared with the IAF films are as follows: The IBF films have no excess iodine molecules (I-2) to form a complex with nylon 6 chains because those molecules in the iodinated powders have been evaporated through the melt press. The IBF films have a practically amorphous structure but only a few crystalline portions with a relaxed state which may have been created with iodide-ion-free segments of nylon 6 molecules through the procedure of film forming. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1138 -1144, 2003.