When willow and water were heated rapidly (7-16 degrees C/s) to high temperatures and high pressures, most of willow (90 vol %) dissolved in water at 341 degrees C in 2.5 s without complete dissolution. Adding 0.8 wt % Na2CO3, complete dissolution of willow (concentration up to 35 vol %) was observed at 329-367 degrees C and water densities of 322787 kg/m(3) (14-106 MPa) in 1.5 s. By cooling the solublized willow immediately, micron particles were obtained via precipitation. If heated further to 400 degrees C, willow was completely hydrolyzed to sugars/sugar oligomers in 14.6 s at homogeneous conditions. A flow reactor was proposed to completely solubilize willow for the production of micron particles, sugars, bio-fuels and chemicals continuously. (C) 2008 American Institute of Chemical Engineers.