A thiocarbonylthio compound and free radical polymerization employing the same. The thiocarbonylthio compound is represented by formula (I) or (II): wherein Z can be independently perfluoroalkyl, alkyl, haloalkyl, aryl, alkylaryl, haloalkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, alkoxyaryl, alkylsulfonyl, alkylsulfonylaryl, dialkylphosphinyl, or dialkylphosphinothioyl; R1 and R2 can be each independently hydrogen, alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl; R3 is alkyl, aryl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl. Furthermore, R3 can also be alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, haloalkylaryl, alkylsilyl, alkylthio, alkylthioaryl, or substituent containing CN, CO, COOH, COOCH3 or heterocyclic moieties; and R4 is perfluoroalkyl. The thiocarbonylthio compound can be used as a reversible chain transfer agent in a free radical polymerization to obtain a polymer with a controlled molecular weight and narrow polydispersity.