A series of Ti(IV), Ni(II), Bi(III), and Pb(II) ion-doped electrolytic manganese dioxide samples (EMD) was prepared using MnCl2/HCl electrolyte. The discharge capacity of EMD doped with 0.22% Ti increased by 36% over that of the International Common Sample No. 1 EMD (I.C.1) and by 23.1% over that of a fibrous electrolytic manganese dioxide sample (FEMD). The cycle life of EMD eloped with both 0.23% Ti and 0.24% Bi increased by 200% over that of I.C.1 and 316% over that of FEMD. X-ray photoelectron spectrometry data showed that additional Mn vacancies were present on the surface of doped samples, and that the TiO2 in doped EMD was inserted into the MnO2 lattice. The OH surface area (S-OH) and proton diffusion coefficient, (d(H)i) data showed that when S-OH was near 29 m(2)/g, DH- in EMD was 5.068 x 10(-13) cm(2)/s and the EMD was slightly reduced, doped Ti and Bi EMD samples showed higher initial discharge voltages and the proton was not the only species which controlled the charge/discharge reaction. Thermogravimetric analysis data showed that doped Ti, Ni, and Bi ions stabilize the structure of MnO2 during charge/discharge cycles.