Pyrolysis of extracted oil palm fibers under isothermal and non-isothermal conditions was carried out in a thermogravimetric
analyzer. Isothermal curves showed that increasing pyrolysis temperature resulted in a faster pyrolysis and a higher conversion
of oil palm fibers into gaseous products. Raw material sizes (below 1.0 mm) had insignificant effects on the isothermal pyrolysis,
but the fibers with a size fraction of 1.0 to 2.0 mm resulted in a lesser conversion. Two-step reactions were found in the
non-isothermal pyrolysis as evidenced by the presence of two peaks in the derivative thermogravimetry curves. Raw material
sizes had no obvious effects on the temperature at which the maximum rate of pyrolysis occurred, but affected the rate of
sample mass loss. For the low and high temperature regimes, a three-dimensional diffusion mechanism and a first-order of reaction
mechanism respectively were used to describe the non-isothermal pyrolysis kinetics of extracted oil palm fibers.