Endo-1, 4- β- D-mannanase (EC 3.2.1.78) is a glycoside hydrolase involved in random cleavage of β-1, 4- D-manno-pyranosyl linkages within mannans and heteromannans and generates branched and linear oligosaccharides. A β-mannanase was purified from a thermotolerant bacterium Paenibacillus thiaminolyticus isolated from a soil sample. Enzyme was purified to homogeneity with specific activity of 8812 U/mg protein. Sodium dodecyl sulfate (SDS) and native poly-acryl amide gel electrophoresis indicated that the purified mannanase is a monomeric protein with a molecular mass of 38 kDa. The purified enzyme was found to be maximally active at temperature and pH of 60°C and 7.0, respectively. It was stable at 55°C for 24 h and maintained more than 50 % activity up to 3 h at 60°C. The enzyme was very stable in the pH range of 5.0-9.0. Purified β-mannanase demonstrated high stability after 1 h of pre-incubation with most of the tested organic solvents.   Enzyme retained significant stability in the presence of various detergent additives, commercially available detergents and dish washing liquids. The high compatibility and substantial stability in the presence of nonionic detergents and dishwashing liquids confirmed its utility as an additive to dish washing liquids and laundry detergents. Enzyme exhibited efficacious de-staining of heteromannan based stains of chocolate ice cream and salad dressing in the wash performance test for detergent application. It also exhibited anti-soil redeposition effect on cotton swatches treated with tennis court clay and heteromannans.