The measurements of the temperature dependence of the interfacial tension of the Al-Sn alloy by the dihedral angle method gave the following conclusions: The method proposed, including the determination and statistical evaluation of the dihedral angles, is sufficiently rapid and accurate. In further applications, the method should be used in the present state; Only the rolled Al-Sn alloys are suitable for measurements; The measured dependences of the dihedral angle and interfacial tension correspond to the form of the phase diagram of the Al-Sn alloy; The measured values of interfacial tension sigma //S//L of the alloy are in satisfactory agreement with the literature data.