BACKGROUND: The present work aimed to characterize the physicochemical properties of the biosurfactant produced by Bacillus mojavensis A21 and to evaluate its potential use in diesel recovery. RESULTS: The strain B. mojavensis A21 was found to be a potent producer of biosurfactant. Compared with SDS and Tween 80, biosurfactant A21 showed high physicochemical properties in terms of the surface activities and high emulsification index. The biosurfactant A21 reduced surface tension to 30 mNm-1. Biosurfactant A21 was also demonstrated to be stable in a wide range of pH, temperature and salinity. Moreover, it was found that it can solubilize diesel more effectively than SDS and Tween 80. It can be considered as an alternative to chemically synthesized surfactants since it shows high solubilization efficiency towards diesel oil (62% at 0.5 g L-1) in comparison with SDS and Tween 80. CONCLUSION: Biosurfactant A21, owing its high emulsification capacity and its high tolerance to acidic and alkaline pH values and salinity, shows great potential for use in bioremediation processes to enhance the solubility of hydrophobic compounds. (C) 2013 Society of Chemical Industry