Using pH potentiometric measurements, concentration quotient and thermodynamic acid dissociation constants were determined for chlorodifluoroacetic acid. The determinations were carried out in aqueous media at seven temperatures ranging from 20 degrees C to 50 degrees C at an ionic strength of 0.25 mol dm(-3). Standard enthalpies and entropies of the dissociation reaction were also obtained. At 25 degrees C, the thermodynamic values of these properties are K degrees = 0.495 +/- 0.020, Delta H degrees = (-5.0 +/- 1.1) kJ mol(-1), and Delta S degrees = (-23.1 +/- 3.6) J K-1 mol(-1).