Abstract Heat treatment of ceramic-reinforced aluminium matrix composites (AMCs) using a high-power diode laser (HPDL) was investigated. AMCs were treated by irradiation with laser beams of different power and scanning speeds. This resulted in significant changes in the overall appearance and microstructure of the composite material. Contact gauge profilometry and combined SEM–EDXS and XRD analyses were performed to investigate the relationship between changes in the morphology and microstructure to the amount of laser energy delivered. Vickers microhardness and tribological tests were performed to identify changes in the local mechanical properties of the composite material. Laser treatment often improves the properties of AMCs, although setting of the operational parameters is crucial. In fact, small deviations in power and/or scan speed can severely damage the material, leading to deterioration of the microstructure and overall mechanical behaviour.