The aim of the work is to study interface formation between Al2O3 particles and Al(Ca) matrix in dependence of Ca content. Aluminium matrix composites (AMC) subjected to investigation were prepared by gas pressure assisted infiltration of alumina beds with aluminium-calcium alloys. It is shown that alumina particles in the AMC are covered with a monocaldum aluminates layer whose coherence increases with increasing amounts of Ca in the aluminium-calcium alloys. Moreover, Al4Ca intermetallic phases are formed with increasing Ca content and interconnect alumina particles. XRD confirms the presence of both CaAl2O4 and CaAl4O2 ternary phases. However, HRTEM analysis confirmed CaAl2O4 with a rather complex structure containing a high density of stacking faults. It appeared that annealing at 735 degrees C does improve consistency of interface for Al 2 waCa/Al2O3 AMC, but do not affect the thickness of the interface in dependence on annealing time. (C) 2016 Elsevier Ltd. All rights reserved.