Activity coefficients of the Hg and Cd components have been qualitatively calculated for a tellurium‐rich Hg‐Cd‐Te ternary liquid‐phase‐epitaxy growth solution for the growth of (Hg,Cd)Te. A comparison of these values with the corresponding values for HgTe(s), CdTe(s), and binary Hg‐Cd alloys indicates that the activity coefficient for the Cd component is closer to the value for tellurium‐rich CdTe(s), while that for the Hg component lies between the value for Te‐rich HgTe(s), and binary Hg‐Cd alloy of a similar composition.