This paper reports the results of the study of the microstructural and mechanical properties of metal matrix composites (MMC) based on Al-Si matrix alloy and silicon carbide particulates. The scope of the study is to investigate the effects of cooling rate and silicon content on the microstructure and the mechanical properties of MMC. Samples were cast in moulds of different temperature in order to identify the effects of the cooling rate while silicon content was varied from 7 to 12.5 % in the matrix material. The conclusion is that the cooling rate has little effect on the properties unless it is taken to the extreme and the effects of the silicon content is no more pronounced than for non-reinforced aluminium.