Molybdenum disilicide-titanium trisilicide (MoSi2-Ti5Si3) is a ceramic matrix composite (CMC) created for the purpose of improving the mechanical properties of molybdenum disilicide. Five alloys of this CMC were prepared by varying the ratio of volume per cent Ti5Si3 to volume per cent MoSi2. Evaluation of the specimens using the piezoelectric ultrasonic composite oscillator technique (PUCOT) determined the values of Young’s modulus to range from 303 to 378 GPa at room temperature increasing with volume fraction of MoSi2. The values of Young’s modulus for temperatures up to about 400 degrees C for each alloy decrease linearly with respect to increasing temperature. Damping within the specimens is independent of strain amplitude at room temperature, but shows some strain amplitude dependence at higher temperatures. The values of density for the alloys, determined using Archimedes’ method, range from about 5200 to 5900 kg m(-3), and compare favourably with the values determined by the rule of mixtures.