Well-defined AB and BA diblock copolymers were obtained by a one-pot two-step sequential block copolymerization by reverse iodine transfer polymerization (RITP), A being a poly(styrene) block and B a poly (butyl acrylate) block. High monomer conversions during the formation of the first block avoided the purification steps before growing the second block. In a third sequential step, the diblock copolymers were further extended to synthesize ABA and BAB triblock copolymers. Furthermore, the synthesis of ABA and BAB copolymers in only two steps by RITP was investigated starting with the formation of the central block using 2,5-di(2-ethylhexanoylperoxy)- 2,5-dimethylhexane as a difunctional initiator and then resuming the polymerization to grow the external blocks in a second step. The obtained copolymers were analyzed by size exclusion chromatography, transmission electron microscopy, and differential scanning calorimetry. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2476-2484, 2011