Excess enthalpies and partial molar excess enthalpies for the systems octamethylcyclotetrasiloxane + benzene and octamethylcyclotetrasiloxane + carbon tetrachloride have been measured at 25 and 45°C with an isothermal displacement calorimeter. For the first system the directly measured partial molar excess enthalpies of benzene agree, within experimental limits, with those determined from vapour pressure measurements. The measured excess enthalpies have a precision of ±2 J mol^–1 for the benzene solutions and ±0.3 J mol^–1 for the carbon tetrachloride solutions.