The present article describes briefly some of NISTs more recent work on calorimetric standards. New reference-quality measurements of the enthalpy of solution of aqueous sodium chloride, obtained with an adiabatic solution calorimeter, are presented and compared to a previous equation of state for NaCl(aq). Other calorimetric standards that are discussed are potassium chloride used for solution calorimetry and reference materials used for calibration of enthalpy-increment and heat-capacity calorimeters, namely synthetic sapphire (alpha-Al2O3) and copper.