PURPOSE: To obtain the titled compound useful as a synthetic intermediate for agricultural chemicals, particularly herbicides in high yield, by reacting an α- halogenoacetic acid with a carboxylic acid salt in the presence of a quaternary ammonium salt or phosphonium salt, and hydrolyzing the resultant reaction product.

CONSTITUTION: An α-halogenoacetic acid of formula I [X is Cl or Br; R1 and R2 are H or alkyl; R3 is OR' or NR"R''' (R' is alkyl; R" and R''' are H, alkyl or aryl)] is reacted with a carboxylic acid salt of formula II (R is H or alkyl; M is alkalie metal or alkaline earth metal) in the presence of a quaternary ammonium or phosphonium salt as a catalyst in an organic solvent at 0W200°C to give an acyloxyacetic acid of formula III, which is then hydrolyzed to afford the aimed substance glycolic acid of formula IV.