A process for producing a purified
carboxylic acid having “n+1” carbon atoms comprises feeding a
carboxylic acid stream containing a
carboxylic acid having “n+1” carbon atoms, a
hydrogen halide, a lower
boiling point (bp) component, a higher bp component, and others to a first
distillation column; separating a lower bp fraction containing part of the lower bp component and a higher bp fraction containing part of the higher bp component in the first column; withdrawing a
side stream containing at least the carboxylic acid by side
cut from the first column; feeding the
side stream to a second
distillation column; separating a lower bp fraction containing part of the lower bp component and a higher bp fraction containing part of the higher bp component in the second column; and withdrawing a
side stream containing the carboxylic acid by side
cut from the second column to recover a purified carboxylic acid; and the process further comprises feeding at least one first component (A) selected from the group consisting of an
alcohol, corresponding to the carboxylic acid, having “n”
carbon atom(s), and an ester of the
alcohol with the carboxylic acid to the first column, and if necessary water. Such a process ensures reduction of the concentration of the
hydrogen halide in the purified carboxylic acid.