Salt stress is one of several major abiotic stresses that affect plant growth and development, and there are many evidences that silicon can ameliorate the injuries caused by high salinity. This study presents the results of an assay concerning: (1) the effect of NaCl induced salt stress in barely plant (cultivar Giza 123) and (2) the possible mitigating effect of silicon in saline conditions. In these study, different concentrations of NaCl (200 & 300 mM) used singly or in combination with silicon (0.5&1.0 mM potassium silicate). Morphological characters of shoot and roots, membrane stability index, relative water content, sodium, potassium, silica, photosynthetic pigments content and some antioxidant enzymes, as well as leaf electron microscope were evaluated. The results showed that, all parameters analyzed decreased except antioxidant enzymes and sodium content were drastically increased by increased salt levels. The supply of silicon (1mM) has successfully mitigated the effect of salinity at 300 mM NaCl. In conclusion, we affirmed that, salt stress is harmful for cape barley plants and the addition of silicon showed effective in mitigating the saline effects.