The chemical composition has been elaborated as isolation covering on the base of the local natural resources for protection  of  fastening bolts  against corrosion by stray  currents. It was revealed that the covering is water-repellent and dielectric isolating material possessing adhesiveness. The tests of the bolts for fastening the rails to the sleepers of Baku subway with the use of the covering under natural conditions showed that there exploitation term increases several times (from 3–5 to 12–18 months) preventing the corrosive destruction of soil.