Electrospray mass spectrometric analyses of carbonate, carbamate, urea, and guanidine in the presence of sodium ions results in polysodiated complexes of the type, [M (n 1)H + nNa]+, where M is the species analyzed and n = 2 and (or) 3. These complexes are unusual in their high sodium contents and their attractive structures. The [M H + 2Na]+ complexes fragment to produce [Na2NH2]+, Na+, and a product ion resulting from the loss of NH3. The [M 2H + 3Na]+ complexes dissociate to give a number of fragment ions, including [Na3O]+, [Na2OH]+, [NaOCNNa]+, [Na2NH2]+, [Na3CN2]+, and Na+, depending on the elemental composition of M. These dissociation reactions were examined both experimentally by mass spectrometry and theoretically by density functional theory. Reaction profiles as calculated at B3LYP/6-311G** for disodiated carabamate, urea, and guanidine, and for all the bases in trisodiated form are given. Both experimental and theory show [Na3CO3]+ to have high stability towards collisional activation and to preferentially dissociate to give [Na3O]+ and CO2, rather than Na+ and Na2CO3.Key words: carbonate, carbamate, urea, guanidine, electrospray, collision-induced dissociation, density functional theory, sodium ion binding energies.