Abstract. The objective of this study is to determine the effect of epoxy resin on the physico-mechanics, thermal and microstructure properties of geopolymers hybrid composites for geothermal pipe application. Hybrid composite epoxy-geopolymers pipes were produced through alkali activation method of class-C fly ash and epoxy resin. The mass of epoxyresin was varied relative to the mass of fly ash namely 0% (SPG01), 5% (SPG02), 10% (SPG03), 15% (SPG04), and 20% (SPG05). The resulting materials were stored in open air for 28 days before conducting any measurements. The densities of the product composites were measured before and after the samples immersed in boiling water for 3 hours. The mechanical strength of the resulting geothermal pipes was measured by using splitting tensile measurement. The thermal properties of the pipes were measured by means of thermal conductivity measurement, differential scanning calorimetry (DSC) and fire resistance measurements. The chemical resistance was measured by immersing the samples into 1M H 2 SO 4 solution for 4 days. The microstructure properties of the resulting materials were examined by using x-ray diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The results of this study showed that hybrid composite epoxy-geopolymers SPG02 and SPG03 are suitable to be applied as geothermal pipes.