Mercury (Hg) has two NMR active nuclei ¹⁹⁹Hg and ²⁰¹Hg. ¹⁹⁹Hg is a low sensitivity spin-½ nucleus that yields sharp signals over a very wide chemical shift range. ²⁰¹Hg a quadrupolar low sensitivity nucleus that yields signals too broad to be observed with a high-resolution NMR spectrometer even for small molecules such as dimethyl mercury. Therefore, ¹⁹⁹Hg is the mercury nucleus of choice. ¹⁹⁹Hg-NMR is used for the study of mercury compounds, their structure, dynamics and conformation. It is also used for biological binding studies using its relaxation effects.

Each type of mercury has its characteristic chemical shift range.