The Malaysian palm oil industry is growing rapidly, becoming a significant commodity in this country. In 2020, there were almost 5.9 million hectares of land planted with oil palm in Malaysia with a total of 457 palm oil mills. These mills received 96.97 million tonnes of fresh fruit bunch (FFB), producing about 19.14 million tonnes of crude palm oil (CPO) (MPOB statistics, 2020). Besides producing palm oil and palm kernel, these palm oil mills also generated an abundance of by-products such as empty fruit bunches (EFB), mesocarp fiber (MF), palm kernel shells (PKS), and palm oil mill effluent (POME). On the other hand, oil palm fronds (OPF) and oil palm trunks (OPT) are generated at the oil palm plantation from the pruning and replanting processes. These oil palm biomass (OPB) could become alternative materials for other industries such as for the production of biomass pellets, bioplastics, bio-composites, second generation biofuels, green chemicals, etc. For example, OPB has the potential to be utilised as renewable energy to produce synthetic biofuel, power generation (Loh, 2017), bio-ethanol production from lignocellulosic waste (Yanni et al., 2013), biocomposites (Shinoj et al., 2011), and for mulching to increase the FFB yield in plantations (Anyaoha et al., 2018). The OPB has an advantage since it is abundantly available, renewable, and can be converted to be used as cheap feedstocks for other applications, thus reducing the environmental impact of biomass disposal. To increase oil palm biomass utilisation, efforts have been undertaken to investigate pretreatment and preprocessing technologies, particularly on size and moisture reduction for better handling, storage, and suitability for their intended application.