Production of an adsorbent for water treatment with minimum energy, with a green method is the purpose of many researchers. MOFs (Metal-Organic frameworks) are a type of novel porous materials that have many applications in different fields. Owing to their outstanding properties such as high porosity, high specific surface area, these materials are able to be used in different applications such as energy storage, hydrogen storage, and to be applied as water pollutant adsorbents from wastewater. But many of them are unstable in water and their structure will collapse. A highly stable Cerium-based MOF (Ce-UiO-66 MOF) was synthesized in water in a short period of time via a green room temperature synthetic method, activated via methanol reflux for three days at 60 °C, and finally it was characterized. In this project anionic Congo red (CR) dye was used as a model pollutant to investigate the influence of different conditions on the adsorption performance of the resulting Ce-MOFs. XRD and FTIR analyses confirmed the successful synthesis and high stability of this adsorbent after soaking in methanol reflux at 60 °C. N2 adsorption/desorption analysis showed that this MOF has a surface area of 572 m2/g and a pore volume of 0.38 cm3/g. The adsorption kinetic and adsorption isotherm of Ce-UiO-66 were described by the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively. The prepared MOF showed good adsorption performance toward anionic CR dye. The highest adsorption capacity was measured to be about 400 mg/g after 2 h.