Since Malaysia and the surrounding of the South East Asian countries has developed a large amount of oil palm EFB as a waste product after being processed as a fuel or other application, thus oil palm EFB fibre has displayed great potential as reinforcing material in polymer.The aim of this study to characterize the morphological and thermal effects of the seawater treated of oil palm empty fruit bunch single fibres and composites. The fibres of oil palm EFB has been treated using seawater from Pulau Tiga, at day-3 until day-30, the different filler loading of 1%, 3% and 5% of untreated and treated composites were prepared using casting method. The thermal properties of the composites of untreated and seawater treated were analysed using Thermogravimetric Analysis (TGA). Based on the thermal effect, Pulau Tiga composites have the good thermal stability due to the highest onset temperature. The morphological examined using Scanning Electron Microscopy (SEM). The morphological changes enhanced with the seawater treatment, however, at the filler loading of 5%, the composites easily cracked with more voids detected. In conclusion, seawater treatment significantly improved an extra enhancement in thermal stability and the morphological changes improved with the seawater treatment at 1% of the fibre loading