Abstract: The polyetheretherketone (PEEK) based composites filled with nanometer Al_2O_3 or nanometer TiO_2 and polytetrafluoroethylene (PTFE) were prepared by heat compression molding. The influence of the inorganic nano-particulates on the tribological behavior of the composites was investigated on a pin-on-disc test rig, by dry sliding against AISI 1020 carbon steel disc in a pin-on-disc configuration. The worn surfaces of the composites were observed on a scanning electron microscope. It was found that the PEEK composites filled with the nano-particulates of a proper mass fraction and with 10%PTFE recorded smaller friction coefficients and wear rates than the PEEK-based composite filled with 10%PTFE alone. The nanometer TiO_2 as the filler was superior to the nanometer Al_2O_3 in terms of the ability to improve the friction and wear behavior of the PEEK-based composites. This was attributed to the enhanced plastic deformation of the PEEK-based composites in the presence of the Al_2O_3 nano-particulates, which was not observed for the PEEK/10%PTFE/5%nano-TiO_2 and PEEK/10%PTFE/7%nano-TiO_2 composites. It was suggested to pursue further work so as to reach a better understand of the differences in the tribological behaviors and wear mechanisms incorporated with PTFE and different types of inorganic nano-particulates.