Abstarct: In this project, a iron (III)-Poly(vinyl chloride) (PVC)-Shiff baxse adsorbent was prepared for removing methyl orange (MO), a model anionic dye, from aqueous solution. Poly(vinyl chloride) (PVC) was aminated by treating the resin with a concentrated aqueous solution of ethylenediamine. The aminated PVC was then reacted with salicylaldehyde to incorporate the shiff baxse group onto the polymer backbone. The modified PVC was further reacted with iron (III) nitrate to form an iron complex. The prepared adsorbent was characterized by scanning electron microscope (SEM), elemental analysis and infrared spectroscopy (IR). Adsorption experiments were carried out to remove MO from its aqueous solutions using proposed adsorbent. The different parameters affecting on the adsorption capacity such as pH of the solution, contact time, amount of adsorbent, initial dye concentration, temperature, and mixing of the solution have been investigated. Analysis of adsorption results obtained at different temperatures showed that the adsorption pattern on the adsorbent can be described perfectly with Freundlich isotherm models, and the characteristic parameters for adsorption isotherm were also determined. The adsorption process has been found endothermic in nature and thermodynamic parameters have been calculated. The adsorption kinetic followed the pseudo-second order kinetic model. Comparative studies showed that the adsorption capacity of proposed adsorbent is 5–6 and 23-24 times of activated carbon and unmodified PVC, respectively. The results indicate that modified PVC could be employed as effective adsorbent for the removal of methyl orange anionic dye from wastewater.