A water/oil two-phase solution strategy has been developed for the synthesis of various β-Co(OH)_2 nanostructures. More importantly, two different morphologies of β-Co(OH)_2:mesoporous nanowafers and nanohexagons were successfully obtained through one reaction. Furthermore, the special mesoporous of β-Co(OH)_2 nanowafers and nanohexagons exhibited excellent electrochemical hydrogen storage capacities and cycling stability. The maximum capacity reached 265.9 and 215.7 mA hg~(-1) at room temperature, respectively.After 70 cycles, the discharging capacities of the electrode still remain above 218.2 and 175.4 mA hg~(-1), which indicates that the as-prepared mesoporous β-Co(OH)_2 nanowafers have a strong resistance against oxidation and corrosion. These results indicates that the mesoporous β-Co(OH)_2 nanowafers and nanohexagons may be potentially applied for electrochemical hydrogen storage. A more important, two different morphologies of β-Co (OH) _2: mesoporous nanowafers and nanohexagons were successfully obtained through one reaction. Furthermore, the special mesoporous of β-Co (OH) _2 nanowafers and nanohexagons exhibited excellent electrochemical hydrogen storage capacities and cycling stability. The maximum capacity reached 265.9 and 215.7 mA hg -1 at room temperature, respectively. After 70 cycles, the discharging capacities of the electrode still above 218.2 and 175.4 mA hg -1, which indicates that the as-prepared mesoporous β-Co (OH) _2 nanowafers have a strong resistance against oxidation and corrosion. These results indicates that the mesoporous β-Co (OH) _2 nanowafers and nanohexagons may be potentially applied for electrochemical hydrogen storage.