Abstarct: In this study, walnut shell modified with polyaniline was synthesized by chemical polymerization method and its efficiency was investigated for removal anionic methyl orange and congo red as anionic dyes in single and two-component systems. Also, the prepared adsorbent was characterized using FT-IR, FESEM, EDX and cyclic voltammetry techniques. Effect of various parameters such as solution pH, contact time, adsorbent dosage and dye initial concentration on the dye removal was investigated. The concentration and removal percentage of dyes in the two-component system in different laboratory conditions was determined by the ratio difference spectrophotometric method. Also, the isotherm and adsorption kinetics studies showed that the adsorption process in the single and two-component systems follow the Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum adsorption capacity for removal of methyl orange and congo red dyes in the single-component system was 243.90 and 114.94 mg/g, respectively. While in the two-component system, the amount of this quantity was changed to 259.25 and 58.53 mg/g, respectively. Thermodynamic parameters such as ∆H, ∆S and ∆G were also examined. The results reveal that the adsorption procces is endothermic and spontaneous and associated with increasing the entropy.