The ratio of the Larmor frequencies of111Cd and2H has been measured in an aqueous solution of CdSO4 with high accuracy.111Cd chemical shifts have been investigated in aqueous solutions of CdCl2, Cd(NO3)2, CdSO4, and Cd(ClO4)2 as a function of concentration. Using these, the ratio of the Larmor frequencies of the111Cd nuclei for infinite dilution relative to2H in pure D2O is given. From this a g I -factor for111Cd has been derived and has been compared with the g I -factor of an optical pumping experiment. The resulting shielding constant is σ*(hydrated111Cd versus111Cd atom)=-1.106(4) · 10-3. This yields an atomic reference scale for all measured NMR line shifts in the liquid and solid state and the possibility of comparing experimental and theoretical shielding constants. As a consequence, the amount of the Knight shift of metallic cadmium becomes 20% larger.