Thermodynamic data on nickel and its compounds were critically reviewed, evaluated, and compiled by the federal Bureau of Mines. Values of the properties cp deg., S deg., H deg. - H deg. 298, -(G deg. - H deg. 298)/T, ahf deg., Agf deg., and log k are presented in tabular format; cp deg., S deg. - S deg. 298, H deg. - H deg. 298, Ahf deg., and agf deg. are also presented algebraically. Values of ah deg., Ag deg., and log k are tabulated for selected reactions involving nickel compounds, with emphasis on metallurgical interest. Data on auxiliary compounds employed in the reactions are included.