AbstractSelf-consistent (Hartree-Fock) calculations of the process of decomposition of protonated and lithiated syn-N-nitrosourea show that the presence of cations perturbs the electron distribution significantly. The decomposition of nitrosourea is facilitated when a proton or lithium ion is positioned at the oxygen of the nitroso group. These results may suggest clinical experimentation with nitrosoureas used in conjunction with lithium salts.