Structural changes of various RFe2 intermetallic compounds and their conditions for hydrogen-induced amorphization (HIA) are studied with the techniques of X-ray diffraction, transmission electron microscope and pressure-composition isotherms. CeFe2 are amorphized even at 293 K under a hydrogen pressure of 0.1 MPa. SmFe2, GdFe2 and DyFe2 are amorphized in narrow temperature ranges at around 530 K. ErFe2 are not amorphized at such a low hydrogen pressure of 0.1 MPa. For GdFe2, HIA can be obtained at 533 K above an equilibrium hydrogen pressure of 2 kPa. The composition of amorphous hydrides has the hydrogen content above GdFe2H2.2.