First principles calculation, quasi-harmonic approximation, and thermal electronic excitation are combined to investigate temperature-dependent thermodynamic and mechanical properties of Pd50Cu50. It is found that the ordered (B2, L10) as well as BCC and FCC solid solutions of Pd50Cu50 are not only energetically favorable with negative heats of formation, but also mechanical stable. Calculations also reveal that heat capacities of the four structures of Pd50Cu50 at a certain temperature are very close to each other, and that the elastic constants of each structure have a descending sequence of C11 → C12 → C44 within the entire temperature range. Moreover, the B2 structure has the smallest coefficient of thermal expansion as well as brittleness among the four structures, suggesting that the B2 structure of Pd50Cu50 should be more appropriate for hydrogen permeation in terms of thermodynamic and mechanical properties. The calculated results are in good agreement with experimental observations in the literature