The present invention relates to hyaluronic acid ester derivatives, whose carboxylic groups are partially esterified with hydroxy groups of propiophenone derivatives, to the hydrogel materials consisting of the said hyaluronic acid ester derivatives, to their preparation process by photocuring of the hyaluronic acid ester derivatives, and their use in the biomedical, sanitary and surgical fields, and in the medical field as controlled release systems for drugs.