The performance of pultruded GFRP composite exposed to elevated temperatures is investigated. All composite samples were heated to 80 °C, 200 °C, 300 °C, 325 °C, 350 °C, and 400 °C with duration of 15, 30 and 45 min. The samples were then subjected to tensile strengths and mechanical properties were determined. DMA, DSC and TGA analyses as well as burn off tests were carried out. The experimental findings revealed that the 80 °C treatment enhanced mechanical properties in terms of tensile stresses Young's modulus due to post-curing effects. On the other hand, temperatures higher than 200 °C reduced mechanical properties. At 300 °C, tensile stress decreased by 8.7 %, while the Young's modulus was reduced by 10.9 %. As shown, the maximum degradation occurred at the highest temperature of 400 °C, where tensile stress had reduced by 41.3 % and Young's modulus had been reduced by 47.7 % after 45 min. Moreover, detailed damage analyses were performed and structural damage in the form of delamination and cracking was evident at higher temperatures. More importantly is that a mathematical model based on the hyperbolic tangent function was developed and this model accurately predicted the mechanical behavior of GFRP composites exposed to elevated temperature.