A new controlled polymerization reactor is introduced. The reactor design is based on the principles of pulsed initiation polymerization. The 1 l reactor is equipped with a high-voltage UV-stroboscope, the frequency of which can be raised up to 250 Hz. In this reactor pulsed initiation polymerizations of n-butyl acrylate were performed. Results indicate that the use of high pulse frequencies in this set-up may resolve problems associated with chain transfer to polymer in the determination of propagation rate coefficients for acrylates at temperatures above 30 °C.