CH2=CHCOOH was esterified with BuOH at 125 degrees C under 8 bar on an ion-exchange resin catalyst in a flow reactor. The unconverted CH2=CHCOOH was recovered from the reaction mixt. by extn. with aq. NaHCO3 solns. at 20 degrees C. Both an excess of NaHCO3 soln. and addn. of solid NaHCO3 resulted in an increase in CH2=CHCOOH distribution coeff. between act. and org. phases and an increase in the degree of its recovering.