We have shown hollow Ni nanonodules with outer diameters of 80-200 nm and wall thicknesses of 5-25 nm could be prepared by electrochemical deposition in the NiCl2 + dimethyl sulfoxide + C2H4O3 + H2O system, and the products were high purity. In particular, Ni hollow nanonodule structures or highly assembling Ni hollow nanostructures can be selected by varying the compositions of the solvent mixture. Apart from the hollow grain size, the wall thickness can also easily be controlled by varying the electrochemical parameters, salt concentration, and deposition time. The typical coercivity of Ni hollow nanostructures with particle sizes of about 100-150 nm was much bigger than that of the bulk Ni.