Thermodynamic properties of the PbxSb0.25*(1-x)Bi0.75*(1-x), PbxSb0.5*(1-x)Bi0.5*(1-x), PbxSb0.75*(1-x)Bi0.25*(1-x) alloys of the Pb-Sb-Bi system, with the Pb concentration ranging from 3.0 to 87.0 mol. %, were studied by measuring the EMF equilibrium values in the temperature interval from 723 to 873 K in molten lead and potassium chlorides. The Pb-SbBi system activity, activity coefficients, partial and integral thermodynamic characteristics were calculated. The dependences of the excess integral thermodynamic functions are presented.