FIELD: operation of thermal power plants; applicable in transportation and stationary diesels, hot-water boilers and heating systems. SUBSTANCE: additive to water for protection of thermal power plants contains, wt.%: polyacrylamide, 2-6; nickel sulfide, 3-4; sodium hypophosphite, 2-2.5; sodium citrate, 3.5-4; sodium carbonate, 7-11; water, the balance. Use of claimed additive results in deposition of nickel coating on heat-exchange surfaces for continuous protection of heat-exchange surfaces of thermal power plants at temperatures of 75-90 C. To intensify effect, prior to use additive, heat-exchange surface shall be cleaned from products of corrosion and salt deposits. EFFECT: complex protection of internal surfaces of thermal power equipment from cavitation-corrosion attack by introduction of additive with equipment in operation. 1 tbl
