a b s t r a c tActivity of uranium was determine d in gallium, indium and gallium-indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U-Ga-In alloys, uranium forms the intermetallic compound UGa 3 . Activity coefficients and solubility of uranium in Ga-In eutectic were also determine d in the same temperature range. Partial thermodynamic functions of c-U in saturate d alloys wit h gallium, indium and Ga-In eutectic were calculated.