The aim of this paper is to introduce and production of investigate the Al-matrix composites (Al/SiC) reinforced by SiC grains. The specimen are made by powder metallurgy method. During the powder metallurgy the product is made from powder basic materials by pressing and sintering. As a consequence of this technology, the product becomes porous. First of all the porosity has been measured for the time being. In our investigation we tried to find the relationships between the change of parameters of powder-metallurgy technology and the porosity. The characterisation of porosity has started during sintering. In this case dilatometric photos were taken about the behaviour of product during heat treatment, then the density of products and their porosity were measured.