Abstract: The dynamic response of an infinite body with a spherical cavity subjected to a thermal shock is investigated in the context of fractional order thermoelasticity theory proposed recently. The governing equations of the problem based on the fractional order thermoelasticity theory are formulated and solved by means of Laplace transform and its numerical inversion. The non-dimensional temperature, displacement, radial stress and hoop stress are thusly obtained and illustrated graphically. In the calculation, the emphasis is focused on investigating the effect of the fractional order theory on the variations of the physical variables considered. The results show that the thermoelastic coupling effect caused by the applied thermal shock occurs in the infinite body and the fractional order parameter significantly influences the distributions of the physical variables considered.