Rare earth ion (Nd3+/Y3+) and Al3+ codoped α-Ni(OH)2 powers were synthesized by chemical coprecipitation method. The structure was analyzed with X-ray diffraction (XRD) and thermal gravity (TG). Cyclic voltammetry (CV) tests were performed to evaluate the proton diffusion coefficients of the samples. The results indicated that codoping of Y-Al and Nd-Al resulted in more water molecules contained within the crystal lattice and accordingly increased the interlayer spacing. In particular, the Y-Al codoped α-Ni(OH)2 showed a turbostratic structure. The calculated diffusion coefficients of the Y-Al codoped α-Ni(OH)2 and Nd-Al codoped α-Ni(OH)2 were 3.5×10-10 cm2/s and 2.8×10-10 cm2/s, respectively.