Selenium (Se) as essential micronutrient found in foods in the form of organic selenomethionine (SeMet) and selenocysteine (SeCys) in adequate amounts. However, selenite (SeO₃^2-) or selenate (SeO₄^2-) can be found in inorganic form in very low amounts. Higher plants indicate considerable variations in terms of Se requirement with various effects on plant metabolism and uptake of some nutrients. Barley ( Hordeum vulgare L.) is a significant dietary source for this element for humans and animals. In present study, Cys/Met index of Tarm 92 registered barley cultivar subjected to increasing sodium selenate (Na₂SeO₄) doses (6.25, 12.50, 18.75, 25.00 g ha^-1) was investigated. Amino acids were analyzed according to Ion Exchange Liquid Chromatography method by Amino Acid Analyzer AAA 339 M. The experimental soil was analyzed for texture, organic matter, pH, available Phosphorus (P), Nitrogen (N), and Potassium (K). The average Sulfur (S) level in Tarm 92 cultivar was 0.0514 mg 100mg^-1. Results revealed significant effects of Se-treatments on grain Cys/Met index at 12.50 g ha^-1. Average Cys/Met index remarkably increased to highest level at 12.50 g ha^-1. However, at 25 g ha^-1, the level (6.98 mg 100mg^-1) was closer to that in control (5.10 mg 100mg^-1) group. It was concluded in present study that 12.5 g ha^-1 selenium treatment was sufficient to increase grain Cys/Met index of Tarm 92 barley cultivar.