Surface plasma treatment in a reactive ion etching system is used to observe a considerable decrease in permeability of polyethylene terephthalate to gases. The effects of oxygen plasma on the surface properties and morphology of PET polymers are investigated by scanning electron microscopy (SEM), x-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). In addition, the optical transmission properties of the treated samples have been investigated corroborating the findings of SEM and AFM analyses. Moreover, the penetration of air through the treated substrates was investigated using a vacuum test. The treated PET substrates can be used to realize flexible plasma display panels. (C) 2010 Elsevier B.V. All rights reserved.