Based on a paper (S. Chen and S. Lee, 1985) a procedure was developed to det. optimal reaction times for predetd. monomer conversions and no.-av. d.p. in an azeotropic free-radical batch copolymn. with one charge of monomers and initiator. The procedure allows the calcn. of the admissible range of monomer concns., the detn. of an appropriate initiator and its most suitable concn., and the shortest possible reaction times. The validity of the model was tested in the free-radical copolymn. of acrylonitrile and butadiene in PhCl at 343 K, using 1,1'-azobis(cyclohexanenitrile) and AIBN as initiators. The agreement of theor. and exptl. data was satisfactory. The gel effect can be incorporated into the model, and the procedure can also be used in the design of free-radical homopolymns.