Unique polypyrrole (PPy) hydrogels are prepared by using orange IV as the dopant and FeCl3 as the oxidant. The static polymerization of pyrrole monomer in aqueous solution is accompanied with self-assembly of PPy hydrogel. PPy hydrogels not only show good electrical conductivities, but also exhibit excellent water-absorbent behaviors. The macroscopic appearance, microscopic morphology and water-absorbent behaviors of PPy hydrogels can be controlled by the choice of the reaction condition. The effects of ionic strength on the physical properties of PPy hydrogels are also studied. The results indicate that PPy hydrogels show improved water absorbencies in saline solution. Moreover, PPy hydrogel is used as an efficient adsorbent to remove Cr(VI) from aqueous solutions. PPy hydrogel exhibits much better adsorption performance than common PPy nanoparticles. This kind of PPy hydrogel is expected to be a potential candidate for water treatment.