A program conducted to estimate the physical properties of the thermonuclear fusion fuel, D-T (actually the mixture deuterium-deuterium tritide-tritium) is described. The literature is reviewed on the heat capacity and thermal conductivity of solid hydrogen, hydrogen deuteride, and deuterium. Discussions are included on heat capacity and its attendant enthalpy deals with the crystal lattice, rotational, and quadrupolar mechanisms. For thermal conductivity, phonon scattering at crystallite boundaries and self-collisions (Umklapp processes) that reduce the phonon mean free path are described. The effects of rotational energy in either reducing crystallite size or causing phonon scattering from quadrupolar sublevels are discussed. Thermal diffusivity is derived from these properties plus density. An estimate of all the properties for the solid D-T mixture is included. Thermal conductivity and diffusivity prove especially interesting because they may vary as much as five orders of magnitude as a function of temperature, rotational energy, and radiation damage.