Alkali-metal derivatives of the nitrobenzene radical anion have been prepared as stable solids, and their e.s.r. and u.v. spectra interpreted in terms of the radical and its decay products. Solutions of the radical show remarkable stability in a wide range of solvents including water. The e.s.r. spectra of such solutions indicate that significant amounts of tightly bound ion pairs are present in solvents such as acetonitrile and acetone even at radical concentrations of around 10^–4M.