Thermophysical properties, namely, density, viscosity, and electrical conductivity of HgTe and Hg0.9Cd0.1Te melts were measured as a function of temperature. A pycnometric method was used to measure the melt density in the temperature range of 948 to 1073 K for the HgTe melt and 1011 to 1131 K for the Hg0.9Cd0.1Te melt. The density results show a maximum at 1023 and 1020 K, respectively, for the HgTe and Hg0.9Cd0.1Te melts. The viscosity and electrical conductivity were simultaneously determined using a transient torque method from 944 to 1098 K for the HgTe melt and from 1016 to 1127 K for the Hg0.9Cd0.1Te melt. The measured electrical conductivity decreases as the mole fraction of CdTe, x, increases at a specific temperature, and increases as a function of temperature, which shows a semiconductor-like behavior. The measured viscosity decreases as the mole fraction of CdTe, x, increases at a specific temperature and decreases as the temperature increased. The analysis of the electrical conductivity of the melts and the relationship between the kinematic viscosity and density implied a structural transition in these melts. No relaxation phenomena were observed in the density, electrical conductivity, and viscosity of the HgTe and Hg0.9Cd0.1Te melts.