The electrochemical behavior of γ-MnO₂ in lithium hydroxide (LiOH) and potassium hydroxide (KOH) aqueous media has been studied using slow-scan cyclic voltammetry (25 μV s⁻¹) in conjunction with X-ray analysis (XRD) and scanning electron microscopy (SEM). The reduction of γ-MnO₂ in aqueous LiOH results in intercalation of Li⁺ forming a new phase of lithium intercalated MnO₂(LiₓMnO₂). The process is found to be reversible. In this regard, the reduction of γ-MnO₂ in LiOH is quite different from that in aqueous KOH, which is irreversible and no lithium intercalation occurs. This difference in behavior is explained in terms of the relative ionic sizes of Li⁺ and K⁺. The LiₓMnO₂ lattice is stable only for Li⁺ because Li⁺ and Mn⁴⁺ are of approximately the same size whereas KₓMnO₂ is not stable because K⁺ has almost double the size.