Recommended values are provided for chemical thermodynamic properties of inorganic substances and for organic substances usually containing only one or two carbon atoms. Where available, values are given for the enthalpy of formation, Gibbs energy of formation, entropy, and heat capacity at 298.15 K (25 degrees C), the enthalpy difference between 298.15 and 0 K and the enthalpy of formation at 0 K. All values are given in SI units and are for a standard state pressure of 100 000 pascal. This volume is a new collective edition of "Selected Values of Chemical Thermodynamic Properties," which was issued serially as National Bureau of Standards Technical Notes 270-1 (1965) to 270-8 (1981). Values are given for properties of gaseous, liquid and crystalline substances, for solutions in water, and for mixed aqueous and organic solutions. Values are not given for alloys or other solid solutions, fused salts or for substances of undefined composition. Compounds of the transuranium elements are not included.