The dynamic mechanical response of an Al-Li alloy (8090) and SiC particle-reinforced 8090 composite was studied. The strain-hardening behaviour of the alloy was found to change significantly with increasing strain rate. Increasing the strain rate from 10(-3) s(-1) to 6500 s(-1) doubled the strain-hardening coefficient of the alloy. The presence of the particles in the matrix did not affect the strain-hardening coefficient of the alloy. This was attributed to the relatively weak bonding between the particles and the matrix. An orientation effect was observed in the composite samples as a result of the preferential orientation of the reinforcing particles during the extrusion process. The thermal expansion behaviour of the composite samples was found to agree well with Kerner’s model, and provided further evidence of the weak interfacial bonding.