Reversible addition fragmentation chain transfer (RAFT) polymerizations of N-isopropylacrylamide (NIPAM), and acrylamide (AM) were successfully performed in aqueous media at ambient temperature using a redox initiator, potassium persulfate (K2S2O8), and sodium thiosulfate (Na2S2O3). The molecular weight of the polymers obtained increases linearly with monomer conversion, molecular weight distribution is narrow even at high conversion (>90%), and a linear relationship exists between ln([M]o/[M]) and polymerization time. Moreover, self-chain extension reaction also proceeded successfully. All the results demonstrate that K2S2O8-Na2S2O3 is a very efficient initiating system for the RAFT polymerizations of NIPAM. and AM in aqueous media at room temperature.