An oxide ceramic-based composite in the Al2O3-SiO 2-ZrO2 (ASZ) system was developed and investigated using a pressureless sintering route. The effect of the content of each component and sintering temperature upon the microstructure, density, hardness and strength was studied. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to investigate the phase transformation sequences of the ASZ composite system. The flexural strength was measured using three-point bending method on a universal testing machine, while the Indentation Fracture (IF) method was used to determine the fracture toughness of the composite. The results showed that, with varying ZrO2 content, keeping the silica content constant and the alumina as a matrix, densification tends to decrease as the content of zirconia increases from 20 wt. of the composition. X-ray diffraction peaks indicated fully developed alumina, mullite and zirconia phases due to solid-phase reaction and liquid-phase sintering of the system. The experimental results also revealed that, for a sintering temperature of 1500°C, the hardness value ranged from 12 GPa to 14 GPa and the flexural strength was 420±31MPa.The fracture toughness (K Ic) was also reported to be between 4.5 and 5.1 MPa.m1/2, for samples sintered at a temperature of 1450°C. © (2012) Trans Tech Publications, Switzerland.