Thermomechanical behaviour of 2D-SiC f/SiC composites following neutron irradiation and helium implantation was studied. Three-point bending tests were carried out at room temperature (RT) and 1073 K, after neutron irradiation (1.29, 2.69 and 5.23 dpa) at the High Flux Reactor–Petten. Results of RT mechanical tests on helium implanted bars are also referred and discussed. The samples with an accumulated damage dose of 1.29 dpa show a strength decrease and improved bend toughness. For the higher neutron fluences the composite exhibits a brittle behaviour. For helium implanted materials, a strength decrease comparable to that observed for those neutron irradiated at lower fluence is present, but its toughness is reduced.