(Polytetrafluoroethylene) PTFE-like films, deposited by using CHF3/Ar gas mixtures in a plasma reactor, have been used as encapsulation layers in pentacene thin film transistors. The PTFE-like encapsulation layers allow to carry out photolithographic processes without damaging pentacene film. However, the PTFE-like encapsulation layers are not effective in reducing hysteresis of electrical characteristics when measured in air. On the contrary, the degradation of the device electrical characteristics, induced by oxygen diffusion into pentacene film after storing the devices in air, is almost completely suppressed by the encapsulation with the PTFE-like films.