ABSTRACT The expansion of dye pollutants overburdened the environment and consequently increased pollution. Photodegradation and adsorption are one of the most efficient processes for water treatment. Metal oxides have been studied for this application. Amongst of metal oxides, Tin(II) oxide semiconductor and its modification are interesting. In this work, Tin(II) oxide nanoplates/chitosan in an ionic liquid media was prepared. This mild method was done in ethyl pyridinium iodide ionic liquid. The structural character of this composite was examined by XRD, TEM, AFM, and DRS techniques. The TEM results showed that this composite consisted of plate morphology. The photocatalysis experiments were carried out by irradiating in ultraviolet and visible light of dyes containing Blue 133 (B133), and Reactive Red 66 (R66). By combining the good semiconductor properties of Tin(II) oxide and the high adsorption of chitosan, the composite is promising for the photocatalytic removal of organic dyes. The Langmuir adsorption isotherm model was used to study the adsorption-photodegradation process of dye molecules on this composite. The results revealed that the highest removal efficiency of Blue 133 under visible light was 45.48%, whereas achieved under ultraviolet light 98.41%. Also, the degradation percentage of Reactive Red 66 by composite remained 98.85%, under ultraviolet light, the removal efficiency decreased to 46.12%, while visible light. The presence of chitosan enhanced the photodegradation-adsorption properties directed towards visible light.