The hydrophilicity ageing of polypropylene (PP) and polyethylene terephthalate (PET) films treated by nonthermal
plasma usually takes over 150 days. In the present work, the accelerated ageing induced by hydrogen atoms and
ultraviolet (UV) radiation with a wavelength of λ = 253.7 nm was studied. It was experimentally found that the hydrogen
atoms restored the modified polymers to their original hydrophobicity very quickly (within several tens of seconds). UV
irradiation of the modified PP film leads to degradation of the hydrophilic properties in 7-8 hours. The irradiation of PET
film over the first three hours results in the hydrophilicity degradation, but further irradiation improves its hydrophilic
properties. The analysis of the processes in the modified layer of PP and PET films during their ageing is performed.