While addressing the question of Al3+ ion intercalation/deintercalation in MoO3, we unravel that Al3+ ion preferentially intercalates in MoO3 in certain aqueous electrolytes. The Al3+ ion electrochemistry in MoO3 shows stark contrasting characteristics in different aqueous electrolytes. Although very high initial Al3+ ion storage capacity of 680 mAhg−1 is observed, a stable discharge capacity of approximately 170 mAhg−1 is attained after 20th cycle over the measured time (350th cycle) at a specific current of 2.5 Ag-1 (5 mA cm−2) in AlCl3 aqueous electrolyte. AlCl3 aqueous electrolyte exhibits superior benefits than Al2(SO4)3 and Al(NO3)3 aqueous electrolytes in terms of offering higher Al3+ ion storage capacity, long-term stability, capacity retention and minimized polarization.