A hyaluronate lyase (BniHL) was purified to homogeneity from a culture of a deep-sea Bacillus niacin strain JAM F8. The molecular mass of purified BniHL was approximately 120 kDa. The purified enzyme degraded hyaluronan as well as chondroitin sulfates A and C by a β-elimination mechanism. The optimal pH and temperature were around pH 6 and 45 °C for hyaluronan degradation. The enzyme required optimally 2, 50, and 100 mM calcium ions for degradation of hyaluronan, chondroitin sulfate C, and chondroitin sulfate A, respectively. Calcium ions slightly increased the thermal stability of the enzyme. In a genome analysis of strain JAM F8, a BniHL coding gene was identified on the bases of the molecular mass and N-terminal and internal amino acid sequences. The gene consisted of 3411 nucleotides and coded 1136 amino acids. The deduced amino acid sequence showed the highest similarity to the hyaluronate lyase of a Bacillus sp. A50 with 89 % identity.