Superabsorbent hydrogels based on natural polymer, carboxymethyl cellulose (CMC)/sodium alginate (SA) were prepared by ⁶⁰Co radiation as a source of initiation of cross-linking. The effect of different ratios of SA (20, 30, 40, and 50%) on the physical properties of the CMC/SA hydrogel such as gel fraction percentage (GF%), and swelling percentage (SW%) were investigated. It was found that the GF % decreases with increasing SA content in the hydrogel. While the SW% of CMC/SA hydrogel tends to increase with increasing SA content in the hydrogel at constant irradiation dose (2.5 kGy). Morphology of the hydrogels was examined using scanning electron microscopy, which indicates compatibility between CMC and SA. Thermal properties were also investigated using thermogravimetric analysis. It was found that the thermal properties of the hydrogel having different composition were almost the same. The results obtained from ultraviolet–visible spectrophotometric analysis show that the prepared hydrogels can be used in the removal of heavy metals from waste water. The ability to absorb these heavy metals is of great importance from the point of view of environmental pollution.