AbstractThe exchange‐correlation part (xc) to the free energy is numerical evaluated in the RPA at arbitrary degree of degeneracy. The results are compared with numerical data of easy‐to‐use analytic fit‐formulas or Padé approximants of the xc‐term. All together results show very high accuracy at extremly high densities (rs ≈ 1). The agreements disappear between the several formulas for increasing Brueckner parameter rs. Numerical results for the xc‐potentials (pressure and chemical potential) at finite temperatures for an electron‐ion system are given. The xc‐part of the ground state energy of our electron‐ion model is compared with the ground state energy for metallic hydrogen and with Monte‐Carlo calculations.