Abstract: In the present investigation, the effect of load and external heating on the friction and wear behaviour of two Al-based metal-matrix- composites (SiC10 and SiC20, containing 10 and 20 vol.% of reinforcement) dry sliding against a semi-metallic friction material was studied. For loads lower than 200 N wear was by abrasion and adhesion, and friction coefficient was quite high, around 0.45. For loads higher than 200 N, friction decreased with load in both materials, whereas wear increased with load for SiC10 and became negative, because of transfer for SiC20. External heating induced a decrease in wear of both composites (and was negative in both cases) but also an unacceptable decrease in friction and increase in wear of the counterface friction material. The particular friction and wear behaviour displayed by the materials under study was explained making reference to the characteristics of the transfer layer, which forms on the surface of the rotating disc.