Absorptive potential of barley straw conditioned in water with respect to the properties of interior and exterior surface of the stalk and leaf is discussed. The contact angle for water and decane, both on dry and wet straw was measured. The internal and external surface of the stalk as well as of the leaf remained preferentially oleophilic when dry, regardless of the straw decomposition time. In the case of straw conditioned in water the external stalk surface exhibited oleophilic properties for 10 days whereas that of the leaf for seven days. During decomposition a wax layer on epidermis was removed. Decreasing accuracy of contact angle determination after 14 days of decomposition was caused by growth of microorganisms on the straw surface. (C) 2003 Elsevier Ltd. All rights reserved.