Heat capacities of anhydrous liquid hydrofluoric acid and of HF saturated with 2-methylpropane are reported. The heat capacity of slightly compressed liquid HF is (2.66 and 2.80) J . g(-1). K-1 at (25.1 and 45.9) degrees C, respectively. The heat capacity of liquid HF slightly compressed and saturated at 24 degrees C with 2-methylpropane (3.7 mass %) is 2.58 J . g(-1). K-1 at 24.3 degrees C. Accuracy is within 2%. These are the first available data for the heat capacity of liquid HF above its normal boiling point. A temperature-pulse calorimeter is described.