Abstract The risk of losing well integrity due to corrosion is very high especially when existing steels are not compatible with downhole fluids. For example, geo- thermal well fluids may pose high corrosive loads on the casing and tubing used to complete the well. Currently, the composite pipe manufacturing pro- cess has been improved allowing fabrication costs reduction and thus pushing the composite pipes to enter the market of well completion. High tempera- ture is known to be unfavorable for the implementa- tion of composite pipes in high enthalpy geothermal wells applications. However, low enthalpy applica- tions where the fluid temperature is lower than 150°C can be a good candidate for such applica- tions. Nevertheless, oil and gas wells are usually at lower temperatures and thus there is a general inte- rest to use composite pipes in such wells. This artic- le presents the experiments performed on several fi- ber glass composite pipes to understand its response to thermal cycles and the results found show that thermal cycling may reduce the pipe strength with up to 10%. The tests have been carried out for a time frame of 3 weeks, and some samples have been continuously heated, while others have been heated for 8 hours and left to cool for 16 hours. Additio- nally, internal pressure tests have shown a new and unique failure mode which is specific to composite pipes. The results indicate that although composite pipes have an increased resistance to corrosion, the current manufacturing process of those pipes might need improvement in order to ensure high well inte- grity in various wellbore applications.