Characterization of an hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel was performed by changing the number of side arms in a PEO molecule. Verification of grafting chemistry and mechanical strength, as well as swelling behaviors and surface morphologies of the HA-PEO hydrogels were analyzed by employing different x-linking molecular weights (MW) of PEO ranging from 1.7 to 5.0 kDa at a fixed low MW HA in the hydrogel network. Methacrylation to the HA successfully obtained via Michael type reaction between the methacrylate arm groups in HA and the thiol end groups in PEO was observed by XPS. Hydrogel formation was markedly dependent upon the numbers of thiol groups in the PEO molecule. Furthermore the lower MW PEO-based HA hydrogel demonstrated stronger mechanical properties but lower water absorption and the smaller pore sizes on its surface and cross section.