In this work, pyrolysis characteristics were investigated using thermogravimetric analysis (TGA) at heating rates of 5-20 degrees C/min. Most of the materials were decomposed between 330 degrees C and 370 degrees C at each heating rate. The average activation energy was 236.2 kJ/mol when the pyrolytic conversion increased from 5% to 70%. The pyrolysis kinetics of oak trees was also investigated experimentally and mathematically. The experiments were carried out in a tubing reactor at a temperature range of 330-370 degrees C with a reaction time of 2-8 min. A lump model of combined series and parallel reactions for bio-oil and gas formation was proposed. The kinetic parameters were determined by nonlinear least-squares regression from the experimental data. It was found from the reaction kinetic constants that the predominant reaction pathway from the oak trees was to bio-oil formation rather than to gas formation at the investigated temperature range.