The solubility of an inert gas Helium in liquid mercury is calculated in the technically important temperature range from -20 to 350°C. Sources of the initial nuclear and thermophysical characteristics of helium are indicated. The obtained calculated data are processed by the least squares method using the approximating equation. The values of the solubility of gaseous helium, calculated from this equation in the interval from the melting temperature to the temperature of normal mercury boiling, are compiled. The results show the solubility of helium in melted tin in the comparable temperature interval from data. The calculation results confirm the earlier established fact that solubility in the inert gas-liquid metal system is larger, the larger the atomic weight of the solvent.