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 [ether . cation](+) and [ether(2) . 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.