Co-Zn alloy coatings have been electrodeposited on steel in choline chloride (ChCl) based liquid in the presence of various concentrations of water. The conductivities of Co, Zn, and Co-Zn electrolytes were found to improve through enhancing volumes of water. The speciation of Co in a Co-Zn electrolyte was investigated using UV-visible spectroscopy. A negative shifting in the Co species was detected when water was added to Co-Zn solutions. The cyclic voltammetry was used to examine the redox potential of the plating solutions, from which it was found that when water was added to Co, Zn, and Co-Zn electrolytes. The redox maximum frequency rises and changes in a progressive direction. Scanning electron microscopy (SEM) was used to examine the morphologies of films. By enhancing the volume of water, the morphology of the deposited Co-Zn coating was found to change. The compositions of Co-Zn coatings made from the electrolyte with water were found to be 19.83 wt% Zn and 80.13 wt% Co. The roughness of the Co-Zn film deposit was reduced to about 7.642 nm when the deposition was achieved from a bath containing 20% water. The X-ray Diffraction (XRD) technique was involved to investigate the XRD pattern of the Co-Zn deposits.