In order to better understand the thermomechanical behaviors of Ti₃SiC₂ and Ti₂AlC ceramics, sintered by spark plasma sintering process (SPS), ultrasonic pulse echography in “long bar mode” (US) and acoustic emission (AE) techniques are applied. High-temperature investigations of the evolution of Young’s modulus (E) and AE activity are carried out up to 1473 and 1623 K. Results show a decrease of E with increasing temperature which is more marked around maximal temperature of the thermal cycle for Ti₂AlC material. Moreover, the increase of the maximal temperature of the thermal cycle influences the number of recorded cumulated hits. Both measurements (US þ AE) highlight the role of the plastic deformation mechanism (motion of dislocation) activated over the brittle-to-plastic transition temperature.