Different types of dyes are used in textile industries. The Loss of dye within textile wastewaters could vary from 5% for basic dyes to as high as 50% for reactive dyes, leading to severe contamination of surface and groundwater. This study was focused on the removal of textile dye (RR2) through catalytic wet air oxidation process using CuO /AC catalyst. The AC was prepared from water hyacinth root using the physic-chemical activation method and CuO/AC catalyst was prepared from 5wt%Cu/AC through the wet impregnation method. The Prepared catalyst was characterized to know its physic-chemical and morphological properties by FTIR, SEM, XRD, and TGA-DTA instruments. Batch adsorption experiment was carried out using AC and CuO/AC adsorbents to evaluate the adsorption capacity and thermodynamic property. These adsorption experimental results were well fitted in the Langmuir isotherm model than the Freundlich isotherm model and the maximum adsorption capacity (qmax) is 11.68 and 11.12 mg/g for AC and CuO/AC respectively. The adsorption of RR2 dye on CuO/AC is endothermic and spontaneous in the temperature range (298-343K). The influence of operating parameters (catalyst dose (2-6g/L), reaction temperature (70-120 ), and oxygen partial pressure (1-3bar)) on RR2 dye decolorization and COD conversion at a reaction time of (10-120min) were investigated. Complete dye decolorization(100%) and 88.57 % COD conversion were achieved at maximum operating conditions 6g/L of catalyst dose, 120 reaction temperature, and 3 bar of oxygen partial pressure within 120 min of reaction time. To evaluate the reaction mechanism of CWAO, experiments were carried out with free radical scavengers (NaHCO3andCH3OH). The percentage of dye decolorization was 42.91 and 59% in the presence of free radical scavengers NaHCO3and CH3OH respectively. Also, 97.94 and 92% of decolorization was achieved using the reused catalyst for the first and second time respectively.Based on the percentage of germination index of Lepidium sativium seed, the phytotoxicity of the treated dye solution has low toxicity(62.67%) than the untreated dye solution(34.80%).