The new initiator of the polymerization of acrylamide, leading to the formation of crosslinked polyacrylamide, was discovered. The structure of the synthesized polyacrylamide was characterized by XRD, ¹H NMR, and ¹³C NMR spectroscopy. It was shown that 1,3-dimethylimidazolium (phosphonooxy-)oligosulphanide is able to initiate radical polymerization under drying aqueous solutions of acrylamide, even at room temperature. According to XRF data, the synthesized polyacrylamide gel contains 0.28 wt% of sulphur. The formed polymer network has a low crosslinking density and a high equilibrium degree of swelling. The swelling rate of polyacrylamide gel in water corresponds to the first order kinetic equation with the rate constant 6.2 × 10⁻² min⁻¹. The initiator is promising for combining acrylamide polymerization with the processes of gel molding and drying.