The use of thermoplastic resins in the production of glass fiber reinforced polymer (GFRP) composite materials for civil engineering applications has gained increased attention in recent years, mainly due to their ability to be recycled and reprocessed, making them a potentially more sustainable alternative to the industry-standard thermoset resins. However, most aspects related to their mechanical performance and durability have not yet been investigated. This paper presents an experimental study about the effects of elevated temperatures on the mechanical properties of a GFRP laminate produced by vacuum infusion with 0°/ ± 45° E-glass fiber mats impregnated with acrylic thermoplastic resin. The mechanical properties at elevated temperature of the thermoplastic laminate were compared to those of a laminate with the same fiber architecture but produced with an unsaturated isophthalic polyester (thermoset) resin. Tensile, flexural, in-plane shear and interlaminar shear tests were conducted under steady-state conditions, from ambient temperature up to 100 ℃ – therefore including service temperatures and temperatures above the glass transition temperature – to compare the strength and modulus degradation, under different stress states, with the increase in temperature. The results showed that the thermoplastic-based composite is more prone to thermal degradation than its thermoset counterpart. The property retentions were also compared with the temperature conversion factor model of CEN/TS 19101:2022, calibrated for thermoset-based composites. The model was found to provide slightly non-conservative estimates for the degradation of the fiber-dominated mechanical properties of the thermoplastic-based composite, while its predictions for matrix-dominated properties were generally conservative.