A full explanation of the M-effect, namely the reduction of the neon emission spectra practically to only one line of wavelength ½ ¿ nm, when the filling gas is a mixture Ne + Ar + H¾ or Ne + Xe + H¾ is presented.The M-effect is explained by ion-ion recombination according to the reaction Ne · · H Ne £´¾ Ô½µ·H, which feeds selectively the level ¾Ô½ of neon. All observed behavior of the M-effect is explained by polar recombination. Extension of the M-effect to other gas mixtures containing at least one electronegative component is also underlined.