The aim of current study was to test the ability and optimize the decolorization of textile azo Reactive Orange 122 by Streptomyces sp (A5) isolated from dye contaminated soil. The decolorization ability of the isolate Streptomyces sp (A5) was assessed by spectrophotometer at 3, 5 and 7 days in starch nitrate broth media amended with 0.35 g/L of the Reactive Orange 122 azo dye. Different incubation conditions like concentration of the dye, temperature and pH were used in the present study to investigate their effect on the decolorization rate. The potential isolate Streptomyces sp (A5) exhibited significant decolorization ability at 5 days of incubation. The optimum conditions were found for degradation of Reactive Orange 122 azo dye by the isolate Streptomyces sp (A5). The maximum degradations were noticed at 0.3 g/L of dye concentration, 6 pH and 35 °C temperature, respectively. In conclusion, the results of the current study showed that the isolate Streptomyces sp (A5) was effectively degraded the textile dye Reactive Orange 122 azo dye under the optimized conditions.