Abstract <p>Some wear features of polymer composite materials based on polytetrafluoroethylene filled with modified silicon oxide are characterized. The influence of ion-exchange modification of silicon oxide with aluminum cations from aqueous solutions on the surface activity of the filler in the processes of forming polymer composite materials is considered. The textural characteristics of silicon oxide before and after modification are determined using the low-temperature nitrogen adsorption. Using scanning electron microscopy, images of friction surfaces of polymer composite materials are studied to explain the improvement in their performance characteristics, and the elemental composition of the filler before and after processing is determined. The friction surfaces of samples after tribological tests are studied using infrared spectroscopy. It is shown that aluminum cations promote the intensification of tribo-oxidative reactions during the frictional wear of polymer composite materials with a modified filler followed by structuring of the surface layers and the formation of secondary structures on the friction surface, which leads to an increase in the wear resistance of the material by several times compared to a polymer composite material filled with unmodified silicon oxide.</p>