The application of a micro rotating-bomb combustion calorimeter to chlorine-containing organic compounds was tested by determining the standard massic energy of combustion and the Standard molar enthalpy of formation of 4-chlorobenzoic acid at 298.15 K. Experiments with samples of masses in the range 25.5 mg to 39.5 mg led to Delta(C)u(o) = -(19563.45 +/- 4.88) J.g(-1) and Delta(f)H(m)(o) (C7H5O2Cl, cr) -(429.9 +/- 2.2) kJ.mol(-1) in good agreement with the corresponding values recommended in the literature.