B4C reinforced aluminum composites were fabricated by microwave heating of the mixture of B4C (10, 15 and 20wt%) and aluminum powders at 650, 750, 850 and 950°C. The effect of different amounts of B4C on the microstructure and mechanical properties of aluminum matrix was examined. The maximum bending (238±10MPa) and compressive strength (330±10MPa) values were measured for composites sintered at 950 and 750°C, respectively. The maximum hardness (112Vickers) was measured for Al–20wt% B4C composite sintered at 850°C. XRD investigations showed the decomposition of boron carbide and also the formation of Al3BC by heating the composites at 850°C. SEM micrographs showed uniform distribution of reinforcement particles in Al matrix