Electroplating is one of the most technologically advanced methods to synthesize nanophase materials both as coatings and in bulk form. This paper demonstrates the formulation of a processing “window” for nanocrystalline Co-W alloys using factorial design. The microstructural evolution from polycrystalline to nanocrystalline to amorphous Co-W microstructures is shown for electrodeposits produced from a bath containing cobalt sulphate, sodium tungstate, Rochelle salt and ammonium chloride. The effect of operating variables such as temperature and current density is discussed.