Ablation, water etching and gold coating were studied on poly(ethyleneterephtalate) (PET) exposed to DC Ar plasma for 240 s at 8.3 W power. Au layers were sputtered on pristine and modified PET and their adhesion and topography were investigated. The roughness and changes of topography after plasma treatment, subsequent water etching and gold coating were followed using AFM microscopy. The thicknesses of ablated layer and water dissolved layer were determined using gravimetry. A nanoindentor was used to perform microstratch tests of sputtered layers. Water dissolving of thin layer after plasma treatment was confirmed by FTIR spectroscopy. We have found that under the present experimental conditions ca 30 nm thick layer of PET is plasma ablated. The surface topography changes dramatically and surface roughness increases. Another ca 16 nm thick layer was removed under present laboratory conditions after 24hour water etching. Subsequent coating with 50 nm thick gold layer increases surface roughness in all cases of surface modification.