This work is focused on the study of the wear mechanisms occurring during C/C composite friction. The friction experiments are performed on a pin/disc tribometer coupled to a mass spectrometer. This set-up allows the in situ gas analysis in the contact during friction. Worn surfaces and polished sections done perpendicularly to the rubbing surface are characterized at several scales by optical and scanning electron microscopies to follow the degradations of the material induced by friction. The damages are correlated to the flow source, the size of detached particles and the CO2 production in the contact during friction at different temperatures.