Willow without any pretreatment, and water were studied in an optical micro-reactor, diamond anvil cell by rapid heating (7-10 degrees C/s) to high temperatures and high pressures (up to 403 degrees C and 416 MPa), most of willow (89-99%) dissolved and hydrolyzed in water at 330-403 degrees C within 22 s. It was found that low-density water (e.g., 571 kg/m(3)) solubilized almost all willow with particle size less than 200 mu m, and subsequently hydrolyzed to hydrolysates in subcritical water at 354 degrees C and 19 MPa within 9 s. These results were further used to propose a flow process to fast hydrolyze wood in seconds to valuable sugars. (C) 2010 Elsevier Ltd. All rights reserved.