The kinetics of melt transesterification between poly(ethylene terephthalate) (PET), hydroquinone diacetate (HQDA), and terephthalic acid (TA) is examined. The considerably complex system is treated by methods analogous to solution kinetics. A number of assumptions are proposed and validated to simplify the kinetics and to make the analysis tractable. A key postulation is that the reaction originates between HQDA and TA to form a dimer which slices the PET chain. The subsequent coupling of segments re-forms the PET chain with random incorporation of HQDA-TA units. The steady-state approximation is invoked for the rate of generation of dimer. The number of moles of acetic acid, generated in both homopolyesterification (HQDA-TA) and copolyesterification (coupling of segments) channels, is monitored to follow the overall rate of the reaction and to evaluate the individual rate constants. The rate constants obtained for a majority of compositions conform to that predicted theoretically. The kinetic analysis reveals the implicit simplicity of complex systems.