Co-continuous 63%Al2O3/37%Al(Si) composite, known as C-4 composite, was produced by submersion of silica glass specimens in a molten metal bath. The effect of temperature and composition of the metal bath on the reactive penetration rate was investigated. An infiltration speed exceeding 2 mm/h, increasing with temperature, and suitable for practical applications, was observed above 1100degreesC. Mechanical properties of C-4 specimens were measured, at room temperature, and related to composite microstructure. This latter was investigated by optical and scanning electron microscopy, electron probe microanalysis, X-ray diffraction and porosimetry.The strong interfacial bonds between metal and ceramic resulted in low thermal expansion, high stiffness, and good compression and bending strength. On the contrary, the composite showed a rather poor tensile strength, due to a high ceramic percentage and, partially, to porosity. In spite of the low ductility shown by the investigated composite, the metal network provides a toughening effect, which resulted in a ductile micro-mechanism of fracture, localized in the zones characterized by the presence of the metal matrix. (C) 2003 Kluwer Academic Publishers.