The electrodeposition of Zn-Ni in sulfate solutions has been investiga
ted by means of polarization curves, morphological analysis and electr
ochemical impedance using a rotating disc electrode. The polarization
curves showed two parts, the first one related to the Zn-Ni normal cod
eposition and. the second one to the Zn-Ni anomalous codeposition. The
mass transport influenced only the Zn-Ni normal codeposition and had
no influence on the anomalous codeposition. The temperature showed a g
reat influence on the Zn-Ni alloy deposition and affected both parts o
f polarization curves. The electrolyte composition had no influence on
the Zn-Ni anomalous codeposition, but it affected the transition curr
ent density between normal codeposition and anomalous codeposition. Th
e impedance diagrams were obtained in sulfate electrolytes and showed
four loops at low frequency domain at the beginning of anomalous codep
osition: three capacitive loops and one inductive. For the high polari
zations, one of the capacitive loops disappears. These results were di
scussed comparatively to those previously obtained for chloride electr
olyte, in view of establishing a kinetic model for the sulfate electro
lyte.