To increase the binding strength of H2 to the adsorbent, the introduction of coordinatively unsaturated, open metal sites is a viable strategy. However, it is noteworthy that excessively strong binding at these sites would reduce the usable capacity and lead to a high energy cost for hydrogen release, although examples of adsorbents with too strong H2 binding are currently rare. Addressing these challenges requires considering the function of the surface coverage versus pressure. The surface coverage can be described using the Langmuir equation as a simplified model, which is a function of the Gibbs free energy of adsorption and storage (or discharge) temperature and pressure. Therefore, if the temperature and pressures for hydrogen charging and discharging are specified, one can estimate an optimal Gibbs free energy to maximize the surface coverage difference at the charging and discharging conditions. Given an empirical enthalpy-entropy correlation, the enthalpy of adsorption should fall within a range from -15 to -25 kJ/mol for ambient temperature hydrogen storage. This range represents a balance between maximizing coverage of adsorption sites at the charging condition and minimizing the residual adsorbed gas at the discharging condition.