This work concerns the reaction acceleration in bubble enhanced devolatilization (DV) occurring in reactive extrusion (REX), to provide further evidence that overall reactivity can be enhanced by boiling. Using monoesterification of a styrene-maleic anhydride copolymer with an alcohol as a model reaction, the rate increase was determined by comparing the conversions of the samples collected at different screw locations with those predicted from the combined kinetic equation for the bubble free homogeneous system and the RTD information obtained from both the RTD measurements and theoretical calculations. Significant reaction acceleration was observed. The reaction enhancement was found to be more significant than found previously by batch operation. Also, the reaction enhancement beyond the DV zone showed a trend consistent with the previous observations in batch after DV has been halted. Further, we show that the apparent reaction rate increase during continuous REX/DV is caused by local mass transfer effects, in agreement with the previous work in batch. The good agreement between the theoretical predictions and the experimental results, observed here, lends some extended generality to the mass transfer model for reaction acceleration during REX/DV.