New immobilized biocatalysts based on polypeptides containing N- or C-terminal polyhistidine sequences and possessing organophosphorus hydrolase activity were investigated for detoxification of organophosphorous neurotoxic compounds in the flow systems. The biocatalysts were revealed to have a high catalytic activity within wide pH and temperature ranges 7.5-12.5 A degrees C and 15-65 A degrees C, respectively. The immobilized biocatalysts can be dried and reswollen before use with 92-93% catalytic activity remaining after drying and rehydration procedures. The half-lives of the biocatalysts under wet and dry storage conditions were 420 and 540 days, respectively.