Studies of boron-gluconate electrolyte for obtaining nanocrystalline Co–W coatings and its separation by molecular weights of the components is carried out by gel filtration. It is shown that boric acid (as a buffer agent) and sodium chloride (as the agent increasing conductivity) after being introduced into the electrolyte form certain gluconate complexes in the solution. The boron-gluconate complex has a larger molecular weight. Three fractions with different molecular weights including the fractions that contain Co-boron-gluconate and W-boron-gluconate complexes were obtained. It is shown that the formation of certain macromolecular complexes is a slow process, the consequence of which is the dependence of the bulk properties of the electrolyte on time.