Spherical wood particles of various well-defined diameters were fed into a bed of fluidized olivine maintained at temperatures in the range of 700-900 degrees C. The fluidizing gas was either nitrogen or a steam-nitrogen mixture, and the wooden spheres were introduced in two different ways: on to the bed surface and deep into the bed itself. The resulting gas, tar and char yields were found to be influenced by the method of feed introduction as well as by the bed temperature, fluidizing gas composition and wood particle diameter. The total devolatilization time was correlated by means of a power law expression similar to that used for coal devolatilization and having the advantage of being able to fit well the experimental data over the full temperature range in both nitrogen and steam-nitrogen atmospheres. (C) 2008 Elsevier Ltd. All rights reserved.