Evidence is presented for complexation between sodium and potassium cation (1 mM) and the simple ethers dibenzyl ether, bis(p-methoxybenzyl) ether, bis(p-nitrobenzyl) ether, or bis(ferrocenylmethyl) ether (concentration 0.01–10 mM). Complexation was assessed by electrospray ionization mass spectrometry of chloroform–methanol solutions of the ethers and cations. Adducts of the type [ethen·cation]+ and [ether2·cation]+ were observed for each of the ethers along with [CH3OH·cation·ether]+. These species presumably arise from the chloroform–methanol solvent but [CH3OH·cation·ether]+ are never dominant. A clear correlation of adduct stability with ether donicity was observed and suggests that complexation between ethers and cations can be assessed quantitatively by this technique.