Copolymers from vinyl ester pairs including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as an in situ generator of the transfer agent and 2,2'-azobis(isobutyronitrile) as the initiator at 70 A degrees C. Individual and overall conversions of the comonomers as well as compositions of the comonomer mixture and the produced copolymer were determined from H-1 NMR spectra recorded at various times. Reactivity ratios of VAc and VBz were calculated to be 0.52 +/- 0.18 and 1.62 +/- 0.43, respectively, by extended Kelen-Tudos (KT) method. Experimental and theoretical drifts in the comonomer mixture and copolymer compositions with conversion were evaluated, where theoretical values were calculated from Meyer-Lowry equation using reactivity ratios obtained from extended KT method. A good agreement between the experimental and theoretical values was observed, indicating that reactivity ratios estimated in the present work are accurate. It was also found that produced copolymer has a statistical structure. Attempts were also made to estimate ratio of as a function of initial feed composition.