[en] This paper describes tribological experiments carried out with polyetheretherketone (PEEK), filled with carbon fibres and solid lubricants (polytetrafluoroethylene (PTFE), graphite or MoS₂), against steel discs. Oscillating sliding tests were performed in high vacuum environment in the temperature range between -40 deg. C and +160 deg. C. Results indicate that MoS₂ filled PEEK show the best tribological performance in vacuum. Particularly, in the lower temperature range and at higher loads the friction behaviour is improved by the MoS₂ content