The characteristics of tar generated from tropical-plant-based biomass with different chemical compositions during high temperature gasification are crucial to understand the tar formation. In this paper, lignin-rich palm kernel shell (PKS) and hemicellulose and cellulose-rich coconut shell (CS) were gasified in a downdraft fixed-bed reactor at 900 °C. Fourier transform infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC-MS) were used to examine the functional groups and tar compounds. The results of FT-IR indicate that the PKS tar has a lower intensity peak in the fingerprint region than that of CS. The GC-MS results exhibits that the higher molecular weight of tar compounds, such as polycyclic aromatic hydrocarbons (PAHs) are higher in CS tar compared to that in PKS tar. PKS tar is susceptible to create a lighter molecular weight of tar compounds, such as phenolics. Both of the materials have a great potential to be used for renewable energy feedstock. © Published under licence by IOP Publishing Ltd.