This product is derived from the extremely thermophilic bacterium Pyrococcus abyssi (P. abyssi) and obtained through recombinant expression and purification. Thermostable RNase H is an endonuclease that specifically recognizes and cleaves the RNA strand in RNA/DNA heteroduplexes, without cleaving sSDNA, dsDNA, and exhibits minimal cleavage activity towards single-stranded RNA. Thermostable RNase Hll cleaves at the 5' end of ribonucleotide residues, generating a 5'-phosphate group and a 3'-hydroxyl group after cleavage. This Thermostable RNase Hll exhibits optimal activity within the temperature ranging from 60 to 80°C, remains active between 37°C and 95°C, and exhibits low activity at room temperature. The product is extremely thermostable, with almost no activity loss following incubation at 95°C for 15 minutes, making it compatible with various PCR reaction systems.