The alkaline cellulase produced by alkalophilic Bacillus sp. N6-27 was purified to electrophoresis homogeneity by (NH4)2SO4 fractionation, Sepharose CL-4B hydrophobic interaction chromatography, Bio-gel P-150 chromatography. The molecular weight and pI determined by SDS-PAGE and by PAGE-IEF were 94,000 and 4.2, respectively. The optimum temperature and pH for the enzymatic catalysis were 55 degrees C and 8.5, respectively. The enzyme activity was stable under 50 degrees C and in the pH range of 6-11. The substrate was carboxymethylcellulose (CMC). The enzyme activity was strongly inhibited by Fe2+, Cu2+ and Hg2+.