Abstract <p>The effect of ultrahigh frequency (microwave) curing on the microstructure and mechanical properties of three-component epoxy resins (ER) and glass fiber reinforced polymer (GFRP) has been studied. A comparative analysis of the manufactured samples of ER and GFRP cured by both traditional thermal and microwave methods was carried out. The optimal parameters of the microwave curing process for ER and GFRP were determined, which made it possible to obtain samples with high strength properties under standard tensile and bending tests. Comparative fractographic and microstructural studies of transverse fracture surfaces for ER samples cured by thermal and microwave methods were carried out using scanning electron microscopy (SEM). It has been established that the curing of ER by the microwave method leads to an increase in the size of globules and the number of pores in the material, a more pronounced local plastic deformation during the destruction of the sample, and to a greater variation in the ratio of the propagation velocities of the main and secondary cracks. Comparative studies of the microstructure of the cross-section surfaces and longitudinal cleavage surfaces were also carried out for GFRP samples cured by thermal and microwave methods. It was found that for GFRP samples cured by the microwave method the fracture during longitudinal cleavage is mainly cohesive, caused by the propagation of a crack through the matrix material.</p>