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While forward osmosis (FO) has great potential to be the next generation water treatment technology, it is constrained by the development of ideal draw agents and membranes. Herein, a series of copolymerized hydrogels based on strong ionic monomer sodium 2-acrylamido-2-methylpropane sulfonate (AMPS-Na) and thermosensitive monomer -isopropylacrylamide (NIPAM) have been synthesized and used for the first time as draw agents in the FO process. The effects of the composition of poly(NIPAM- co-AMPS-Na) [P(NIPAM- co-AMPS)] hydrogels and operational conditions including draw agent concentrations, temperature, membrane orientation, salinity of feed solution, velocity of feed solution, and running times on the FO performance have been evaluated systematically. The results demonstrate that the water flux increases with increases of the content of AMPS-Na incorporated into the hydrogel and hydrogel concentration in the draw solution, e.g., from 0.40 LMH rising up to 2.85 LMH. Besides, the water flux increases by 18% as the temperature increases from 5 to 27°C. In addition, these hydrogels remained active even after five times regeneration and reuse with a total water flux decrease of less than 5%. Furthermore, these hydrogels have negligible reverse diffusion through the FO membrane as compared with the corresponding monomer mixture and NaCl, which may avoid possible contamination on the feed solution and lower the renewable cost. All these results indicate that these synthesized P(NIPAM- co-AMPS) hydrogels are promising draw agents for the FO process. [ABSTRACT FROM AUTHOR]