We consider the energy dissipation associated with fracture of a beam at low temperature. A two-dimensional finite element analysis is used to compute the stored elastic energy in the test beam assembly just prior to fracture and to interpret the experimentally determined heat output. By utilizing the Laplace transform technique, the dynamic fracture response of the beam subjected to pure bending is also studied, and instantaneous crack length, crack tip speed and fracturing section bending moment are obtained. The amount of energy dissipated during cryogenic fracture of the beam is calculated using a dynamic strain energy release rate, and the conversion rate of the dissipated energy into the interpreted heat output is estimated.