The amino acid sequences of N-terminal and internal peptide of OPHC2, purified from Pseudomonas pseudoalcaligenes strain C2-1 in our lab, are determined. The full-length organphosphorus hydrolase gene ophc2 is cloned by PCR using the degenerate primers designed according to the sequences and future inverse PCR. The ophc2 gene is 975 bp long with G+C content of 63 %, comprising one open reading frame encoding a polypeptide of 324 amino acids with a molecular weight of 36 kD. The nucleotide sequence of ophc2 shows low homologies with those organphosphorus hydrolase genes deposited in GenBank, one of which exhibits the highest homology of 46.4% with ophc2. The organphosphorus hydrolase protein expressed in E. coli bears normal bioactivity.