Our study focused on the mitigation role of exogenously applied hydrogen peroxide (H2O2) in eliminating toxicty caused by salt (NaCl). Barley seeds were pretreated with 30 mu M (micromolal) H2O2 for 24 hours and then exposed to increasing salt concentrations (0.0, 0.25, 0.275, 0.30 M). Morphogical and physiological changes in seed germination and seedling growth stages were compared between different treatments of salt in laboratory conditions. Adverse effects of salt during both germination and seedling growth stages were dependent on the concentration of the salt treatment. We found that the application of H2O2 effectively alleviated the salt-induced inhibition, and reduced the negative effects of salt on germination (germination index and vigor index), seedling growth stages (radicle and coleoptile lengths, fresh weight), and leaf parameters (stomata and epidermis counts, stomatal index, stomata sizes of adaxial and abaxial surfaces). The differences were statistically significant. Alleviating the effects of H2O2 increased in parallel with salt concentration (p <= 0.05). However, under non-stress conditions (control), H2O2 didn't have any effect on the investigated parameters (p >= 0.05). Our results suggest that exogenous H2O2 application is involved in the resistance of barley to salt stress.