New hydrogels, unloaded and loaded with ammonium nitrate (NH4NO3), have been prepared by free radical copolymerization of acrylamide (AM), acrylic acid (AA), hydroxypropyl acrylate (HPA) and glycidyl methacrylate (GMA), ammonium persulfate (APS) as initiator in water and ammonium nitrate solution, respectively. The hydrogels were characterized by infrared spectroscope (IR) and scanning electron microscopy (SEM). Swelling behaviors of non-loading hydrogels were evaluated by gravimetric analysis. Non-loading hydrogels showed enormous swelling in water, and swelling characteristics were dependent on not only the chemical composition of the hydrogels, but also the synergetic effect of functional groups. Dynamic swelling behaviors of copolymeric hydrogels followed non-Fickian process. The hydrogels were also loaded with ammonium nitrate as a model agrochemical, and the release behaviors of hydrogels with different chemical composition and percent loading were investigated. (c) 2006 Elsevier Ltd. All rights reserved.