A study of butyl acrylate/vinyl acetate (BA/VAc) batch emulsion copolymerization was carried out in a 5L stainless steel and a 1.2L glass reactor. Conversion and copolymer composition were monitored off-line using standard techniques (i.e. gravimetry, gas chromatography and (1)H-NMR spectroscopy) and in real-time, in situ using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The basis for in-line polymerization monitoring using ATR-FTIR spectroscopy in this work was the change of the intensity of characteristic peaks of monomers with time. Real-time peak profiles (absorbance vs. time) of the monomers were used to calculate conversion and copolymer composition for real-time ATR-FTIR monitoring. The data obtained using the ReactIR(TM) 1000 reaction analysis system showed good agreement with data obtained using standard techniques. In addition, there were indications that this technique can be used for early detection of catastrophic coagulation inside a reactor. The limitations in real-time monitoring of BA/VAc emulsion polymerizations using ReactIR(TM) 1000 were also investigated.