A method to manufacture stable water-in-oil polymer emulsion with low viscosity by using special stabilizing surfactant package is disclosed.

The invention relates to an ethylene cationic polymer comprising at least one primary, secondary or tertiary protonable amine function which is at least partially neutralized by a polymer organic acid neutralizing agent which contains at least one carboxylic, sulphonic and/or phosphonic acid function. Said invention also relates to a cosmetic or pharmaceutical composition comprising said neutralized polymer in a physiologically acceptable medium, in particular, cosmetically or pharmaceutically acceptable medium. A method for cosmetically treating keratinic materials, such as a body of face skin, nails, hairs, eyebrows and/or eyelashes, consisting in applying the inventive cosmetic composition to said keratinic materials is also disclosed.