The flow properties of the highly viscous mucopolysaccharide produced by a marine strain of Pseudomonas (No. 9-12) were investigated. The aqueous solutions of both the native and depyruvated forms of this mucopolysaccharide had yield values even at low concentrations. Flow indices for the native form increased with increasing concentrations, but remained constant for the depyruvated form at various concentrations. The structural viscosity of both the native and depyruvated forms increased with increasing concentration. The spinnability of the native form was determined to be much greater than that hyaluronic acid and potato starch. Electron micro-graphs of the gel of the native form showed microfibrils with network structures.