An extracellular β-glucanase from Bacillus licheniformis has been isolated and characterized. Isolation has been performed by salting out and gel filtration chromatography, yielding a homogeneous active component with a molecular mass of 27 000-28 000 daltons and an isoelectric point of 4.7. In addition to being quite a thermostable protein (optimal temperature 55°C) the enzyme is active under a wide range of conditions including pH (4.0-10.5), and in the presence of a large number of metal ions, sodium dodecylsulphate and ethylenediaminetetraacetate. The simple purification procedure and useful properties make this enzyme suitable for brewing processes. © 1988 Springer-Verlag.