The calculation of hydrogen solubility in metals and disordered alloys with face-centered cubic structures is performed taking into account the formation of hydrogen bicomplexes in octahedral interstitial sites and of crowdions along the space diagonals of elementary cubic cells. The determination and analysis of alloy free energy permits us to ascertain the energetic advantage of the material state with the presence of bicomplexes and crowdions in it, and with that the hydrogen solubility is increased sharply.NOMENCLATUREF Free energyE Internal energyW Thermodynamic probabilityT Absolute temperatureN Number of lattice sites (A, B atoms)a, b A, B components concentrationss Hydrogen solubilitys H , s C Hydrogen atom concentrations corresponding to isolated atoms H and bicomlexes Cs O , s Θ , s Q Hydrogen atoms concentration in octahedral O, tetrahedral Θ and triangular Q interstitial sitesv α H , v α C , v H H Interaction energies of hydrogen atoms H and hydrogen bicomplexes C with nearest atoms α = A, B and of hydrogen atoms between themselves in bicomplexes.