FIELD: chemistry of organophosphorus compounds, chemical technology. SUBSTANCE: invention describes a method for preparing cobalt (II) bis-[1-hydroxyethane-1,1-diphosphonate (1-)] that involves preparing cobalt (II) salt in the concentration 0.7-1.5 mole/l and 1-hydroxyethane-1,1-diphosphonic acid in the concentration 1.5-4.0 mole/l an aqueous solution followed by crystallization of product, separation of precipitate from solution and its drying. Method can be realized also using cobalt (II) and 1-hydroxyethane-1,1-diphosphonic acid an aqueous solution taken in the concentrations 0.1-0.3 mole/l and 0.3-3.0 mole/l, respectively, where a water-soluble organic solvent is added to an aqueous solution additionally. Method provides enhancing yield and retaining the homogenous and crystal structure of product. These organophosphorus compounds can be used for preparing electrolytes in galvanic and chemical cobaltization and for preparing other organophosphorus substances used as microfertilizers in agriculture also. EFFECT: improved preparing method, elevated yield. 8 cl, 1 tbl, 10 ex
