Hydrogels in the form of rods were prepared from the ternary systems n-vinyl 2-pyrrolidone/ crosslinking agent/water, in composition ranges where the three components were completely miscible. Gelation was achieved by irradiating the systems with gamma-rays at ambient temperature. The incorporation of water into the binary system of monomer/crosslinking agent reduced the gelation dose 120-fold. The influence of dose, functionality of the crosslinking agent, and relative amounts of crosslinking agent and water on the swelling properties, diffusion behaviour of water and mechanical properties of the hydrogels were investigated. Hydrogels with swelling capabilities in the range 140-420% were obtained with tensile strength values between 0.721 and 2.717 MN m-2.