Hydrogels are hydrophilic cross-linked polymers that can absorb water several times their weight. In this study, synthesis of hydrogel based on chitosan, acrylamide and itaconic acid is prepared via radical copolymerization studied. To study the effect of initiator concentration, time, temperature, cross-linker concentration, monomer amount and itaconic percentage on the water absorption and grafting percentage of copolymerization reaction, experimental design was performed using response surface method. The determined R-2 for the quadratic models for both grafting percentage and water absorption showed values greater than 0.9, which confirm that the model is properly fitted the obtained experimental data. The optimum conditions for maximum water absorption determined by RSM are: initiator concentration 9.51 mMol/L, time 5.27 h, temperature 79.97 degrees C, cross-linker concentration 42.77 mMol/L and itaconic percentage 18.42%. Synthesized hydrogel is characterized using FTIR and thermogravimetric analysis and scanning electron microscopy. The results indicate the porous structure of the hydrogel; thus, this porous natural-based hydrogel can be used in variety of applications such as medical and environmental fields as a drug carrier or water treatment application.