Synthesized is a series of compositions by interaction of water-soluble amines (polyamines) with formaldehyde, and such compositions show properties of H2S neutralizer, biocide and corrosion inhibitor. Stated is a 100% reduction of sulfate-regeneration bacteria grouth under ionization of 100-150 %mg/l and 70% corrosion prevention under concentration of 300-500 mg/l. Noted is a high efficiency of the new agent, which shows complex character of functioning.