An efficient expression system for producing catalase in Bacillus was developed. A catalase was purified from Bacillus sp. TE124 and the catalase gene was cloned by plaque hybridization with a probe constructed from the N-terminal amino acid sequence of the enzyme. The gene, containing an open reading frame of 1452 bp, was subcloned into pHY300PLK for self-cloning into the organism. As a result, the production of catalase increased 20-fold over that of the parent strain.