Different amounts of malonic acid (MAc) containing acrylamide (AAm) hydrogels were obtained in the form of rods via a radiation technique. Swelling experiments were performed in water at 25 degreesC, gravimetrically. The influence of absorbed dose and malonic acid content of the hydrogels on swelling properties were examined. Diffusion behaviour and network parameters were investigated. Swelling of AAm/MAc hydrogels is increased up to ca. 900%, while pure AAm hydrogels swelled up to ca. 700%. Water diffusion into hydrogels was found to be non-Fickian in character. Diffusion coefficients of AAm/MAc hydrogels were calculated by the short time approximation and found to be 6 4 x 10(-7)-10.4 x 10(-7) cm(2) sec(-1). A possible mechanism for AAm/MAc hydrogels was also suggested.