This paper will discuss the nature of the gas induced damage in a poly(vinylidene fluoride) (PVDF) exposed to ＇explosive＇ or rapid pneumatic decompression in a carbon dioxide environment. Generally, under high pressure, the polymer absorbs significant amounts of gas. The large quantity of gas absorbed may induce a dilatation of the specimen and also influence the mechanical properties of the polymer. When the ambient pressure is reduced, the polymer will often suffer irreversible mechanical damage; this process is usually termed explosure decompression failure or ＇XDF＇. This paper is presented in four parts. The first part will describe the variation of the mass of the PVDF polymeric sample in a carbon dioxide medium during the compression and the decompression process at 80 degrees C in the pressure range of 0.1-30 MPa. It is shown that the mass of the specimen increases as the pressure increases but, upon decompression under the conditions described, it is quite constant until 15 MPa and then it falls rapidly. The second part describes the corresponding volumetric change of the polymer, in situ, during the compression and the decompression at 80 degrees C. The decompression curve exhibits a dilatation peak centred at around 14 MPa. The decrease of the mass and the size of the sample is related to the generation of cracks in the polymer matrix during decompression. The third part will describe the results of a mechanical deformation experiment on samples exposed to compression-decompression cycles which is used to establish a relationship between the loss of mechanical properties of the sample and the loss of internal coherence due to the presence of internal cracks. A final part summarises the major conclusions which indicate conclusively that the polymer is irreversibly damaged in the decompression process adopted in the current study.