The interaction of elemental mercury with ice surfaces based on the migration behaviour at sub-ppt concentrations in a packed bed flow tube is discussed. Analysis shows that elemental mercury interacts only weakly with ice surfaces and suggests an adsorption enthalpy of -28 kJ/mol. The experiments further reveal an adsorption equilibrium constant, which quantifies the partitioning of elemental mercury between the surface and the gas phase, with a value of 12 cm at 140 K. Extrapolation to environmental conditions gives a range for the equilibrium constant of 3 × 10-4 to 4 × 10-3 cm at 230 K.