The electrochemical mechanism of Ni electrodeposition in an acid sulfate medium with pH ranging from 1 to 6 is evaluated. For pH < 3, a reaction model already available in the literature accounts satisfactorily for the experimental results shown in Part I of the present paper. However, this model cannot explain the results obtained in the pH interval of 4-6. A complementary model is then proposed, considering the formation of two species: (i) [Ni(OH)](ads)(+), the relaxation of which is associated with a capacitive loop at medium frequencies, and (ii) [Ni(OH)](ads), the relaxation of which gives rise to an inductive loop at low frequencies. The validation of this model has been accomplished by the comparison with the experimental polarization curves and impedance measurements. A good agreement is found between the simulated and experimental results. By using the previous model proposed by Epelboin [J. Electroanal. Chem., 119, 61 (1981)] for pH < 3 together with the present complementary model, Ni electrodeposition can now be explained in the whole pH range of 1-6.