The low-temperature heat capacity of 3,6-dichloro-2-methoxy-benzoic acid was precisely determined with an automated adiabatic calorimeter over the temperature range from 78 to 402 K. The sample was observed to melt at 388.15 +/- 0.03 K, The molar enthalpy and entropy of melting as well as the chemical purity of the substance were determined to be 22244 +/- 35 J mol(-1), 57.31 +/- 0.09 J mol(-1) K-1 and 99.31 +/- 0.02 mol%, respectively. The extrapolated melting temperature for the absolutely pure compound obtained from fractional melting experiments was 388.52 +/- 0.08 K.