The mechanical properties of neutron irradiated Fe–Cr ferritic model alloys with various concentrations of Cr and minor solutes (Ni, Si and P) were investigated along with high-Cr ferritic/martensitic steels. The neutron irradiation was performed in a materials test reactor at two temperatures, 290 ∘C and 450 ∘C, reaching a dose of 0.11 dpa. Tensile tests were subsequently performed on small flat specimens. Significant hardening of about 225 MPa was observed only in model alloys containing Ni, Si and P solute atoms, irrespective of the Cr content and the irradiation temperature. These results suggest that Cr solutes play lesser role in irradiation hardening of ferritic/martensitic alloys steels than previously believed, while minor solutes have a clear effect.