The induced codeposition of iron group metals with refractory metals (W, Mo, Re) falls into the category of so-called “anomalous” electrodeposition, as the refractory metals cannot be electrodeposited alone from their aqueous solutions. However, in the case of electrodeposition from solutions containing salts of the iron group metals (Fe, Co, Ni), their codeposition in the form of alloys having a high content of a refractory metal and possessing some unique physicomechanical properties occurs [1]. However, the mechanism of this process is not completely understood [2 – 4]. We need here the most important answer to the question whether the alloy is produced due to electrodeposition from the corresponding heterometallic complex that is formed directly in the electrolyte [4] or it is the consequence of reduction from the intermediate which contains a metal from the iron group and a refractory metal and is generated through the electrochemical reaction (see, for instance, [2, 3]). In order to find the answer to this question by the example of a citrate electrolyte to produce Co-W alloys, its gel-chromatographic separation into components with different molecular masses has been carried out (see also [5]). In some cases, water was used as an eluent in gel-chromatographic separation (mode at absence of the citrate ion); in other cases, was a buffer mixture consisting of all the components of the electrolyte with the same concentrations except for Na2WO4 and CoSO4 (mode at large excess of the citrate ion). Vitamin B12 was used as compound etalon (certain molecular mass 1355 g/mol). The electrolytes containing (mol/L) CoSO4 (0.2), Na2WO4 (0.2), H3BO3 (0.65), citric acid (0.04), and sodium citrate (0.25) and characterized by different pH values from 5 to 8 were suggested to undergo separation. The results of the performed experiments show that the examined electrolyte to produce CoW alloys contains no elementary substances (components used in the course of its preparation). The electrolyte is a mixture of complex compounds. The more detailed chromatographic study with the use of water as an eluent has shown that the increase in the electrolyte pH (from 5.0 to 8.0) leads to the substantial growth in the molecular mass of the complexes included into its constitution. At pH=5.0, the molecular mass of the complex compounds in the electrolyte is relatively small (much less than 1200 g/mol). At pH=7.0, there are complexes with their molecular masses of about 1200 g/mol in the solution, and, at pH=8.0, these complexes prevail (about 90%). It is shown that only the [Co4Cit4]8- anion and a heteropolynuclear Co-W-citrate complex with the relation Co:W=1:1 are high molecular complex compounds characterized by the above mentioned values of the molecular masses. It is established that a heteropolynuclear Co-W-citrate complex is formed in the electrolyte and the growth in the pH value favorably affects its formation. Obviously, the electrodeposition of the Co-W alloy takes place from the heteropolynuclear Co-W-citrate complex.