Dense polycrystalline Ti3SiC2 samples were fabricated by reactively hot-isostatic pressing (HIPing) a mixture of elemental Ti, Si and C powders. The mechanical properties, including load-strain response, bending strength, fracture toughness and crack propagation, were investigated from ambient temperature to 1573 K. Non-linear stress-strain responses were observed in the polycrystalline Ti3SiC2 materials at ambient temperature. It is conceivable that the inelastic deformation is attributable to micro-deformations that consist of slip between micro-lamellae within individual grains and the formation of microcracks between grains. The polycrystalline Ti3SiC2 exhibited a brittle-to-ductile transition at about 1473K; above this the Ti3SiC2 samples deformed plastically and exhibited high strains (>1.5%), whereas below 1373K only limited inelastic deformation was observed prior to fracture. The mode I fracture toughness, KIC, was measured by the single-edge notched beam (SENB) method to be 4.52MPa m1/2 at ambient temperature. Both fracture strength and fracture toughness decrease only slightly with increasing temperature up to 1273K, above which they decrease more rapidly and reach half of their room-temperature values by 1473K.