Glass Fiber Reinforced Polymer (GFRP) gratings are normally made of two types of processes which are molded and pultruded. It consists of glass fiber and bonding matrixes of vinyl ester (VE), polyester (PE), or phenolic (PHE). The great improvement in strength to weight ratio compare to steel and high resistivity to corrosion makes GFRP grating preferable. However, the use of GFRP grating in offshore is scarce due to issues related to durability and the harsh environment Based on the observation, the accelerated ageing process affects the performance of GFRP gratings by reducing its strength in flexural static load test. Therefore; this study concentrates on the effect of accelerated ageing on GFRP grating. A total of 18 GFRP grating specimens which consist of 6 each of molded Vinyl Ester, molded Polyester and pultruded Phenolic. The entire specimens were aged by immersion in seawater at elevated temperature (60 °C) for the period of 2 month. The main parameters concerns in this study are 1) Max Load vs. Immersion Period, 2) Max Load vs. Deflection graph of results.