Two endoglucanases (EGS and EGT) were isolated from the fungi Gloeophyllum sepiarium and Gloeophyllum trabeum, respectively, rising fractionated ammonium sulfate precipitation hydrophobic interaction chromatography, and gel filtration. EGS and EGT had similar molecular masses (45.1 kDa and 40.5 kDa) and pI values (3.8 and 3.1) and homolog N-terminal amino acid sequences (21 aa). Both enzymes were activated by Ca2+ and Zn2+ and inhibited by heavy metal ions; however; EGS and EGT acted differently on both soluble celluloses and dissolving pulp. Additionally, only EGS was able to cleave galactoglucomannan. On carboxymethylcellulose, EGS and EGT showed K-M values of 7.6 and 6.3 g l(-1) and K-cat values of 92.3 and 86.2 s(-1), respectively. Both enzymes had higher K-M and lower K-cat values on hydroxymethylcellulose. The EGS appeared to act more randomly on CMC and HEC and released larger oligomers from both acid swollen cellulose and dissolving pulp. When added to dissolving pulp in combination with hemicellulases, both of the endoglucanases increased the amount of hemicellulose solubilized when compared to the hemicellulases alone, with EGS showing a more pronounced effect.