In the present study, we apply the Bretonnet-Silbert local model pseudopotential, which takes into account the s-d hybridization in interacting between ion and s-electron to calculate the thermodynamic properties of binary transition-metal liquid alloys. The Wills-Harrison approach is used to take into account the d-electron terms in the free energy. We use the simplest variant of the variational method of the thermodynamic perturbation theory (with the hard-sphere reference system), the Vashishta-Singwi exchange-correlation function, and the Lorenz form of the density of d-electron states. The free energy of mixing, internal energy of mixing, and excess entropy of mixing are calculated for a Fe-Co liquid alloy at different compositions near the melting temperature. The agreement with the experimental data is quite satisfactory.