The Tafel responses [i.e., log(i)-E] of the anodic deposition for hydrous manganese oxide (denoted as MnO(x)(.)nH(2)O) from MnCl(2)(.)4H(2)O with the presence of acetate ions (CH3COO-, AcO-) are systematically examined. Variables studied in this work include the concentration of Mn2+ and AcO- as well as the temperature and pH of the plating solution. The decrease in the Tafel slope for this anodic deposition, defined as (1-alpha)F/2.3RT, indicates that 1-alpha is monotonously increased from 0.18 to 0.4 with increasing the concentration of AcO-. The average reaction orders of AcO- and Mn2+ are about 2/3 and 1/3, respectively. The pseudo-equilibrium potential of the anodic deposition of MnO(x)(.)nH(2)O, obtained from the log(i)-E responses, is linearly decreased with increasing pH of the plating solution (slope = 117.8 mV/decade). The onset potential for the anodic deposition of MnO(x)(.)nH(2)O, examined by linear sweep voltammetry (LSV), is negatively shifted with the continuous addition of acetate ions into the MnCl2.4H(2)O solution. This reduction in the deposition potential is attributed to the formation of Mn-AcO complexes [presumably denoted as Mn(AcO)(delta)(H2O)(6-delta)((2-delta)+)], revealed by the electron paramagnetic resonance (EPR) analyses and the molecular orbital/ligand field stabilization energy theory. The influence of deposition potentials on the mean oxidation state of MnO(x)(.)nH(2)O is also investigated by the EPR analyses. Finally, a scheme corresponding to the anodic deposition of MnO(x)(.)nH(2)O from MnCl(2)(.)4H(2)O with the presence of AcO- is proposed. (c) 2005 The Electrochemical Society.