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Hydrogels based on Poly (vinyl pyrrolidone) (PVP) networks grafted with acrylic acid (AAc) was prepared by the application of gamma radiation of 25 kGy dose from Co-60 gamma source at room temperature (27°C). PVP concentration was kept constant (10%) and acrylic acid concentrations were varied from 0.0 to 2.0% wt. The hydrogel was characterized using FTIR, XRD, DSC and TGA. The FTIR spectra and XRD data indicate the formation of copolymer networks, whereas the DSC and TGA study showed that the PVP/AAc blend hydrogels possess higher thermal stability than PVP hydrogels. Properties such as gel fraction, swelling behaviour, pH sensitivity of PVP/AAc blend hydrogel were investigated. The results indicate that the gel fraction, water absorption and swelling ratio of PVP/AAc blend hydrogel increased with increasing concentration of AAc in the feed solution. Water absorption of hydrogel increases from ~973% to ~2108% for the range of AAc concentration of 0.0 to 2.0% but the swelling is significantly higher when the hydrogel is treated with NaOH solution which is ~3298%.