A process for preparing a fluid powder containing, on a dry weight basis, per 100 parts by weight of the powder, at least 85 parts by weight, preferably at least 90 parts by weight and more preferably at least 95 parts by weight of the minus a deliquescent quaternary ammonium compound, wherein said quaternary ammonium compound is selected from the group consisting of betaine, choline species and tetramethylammonium chloride and bromide, and in which process the fluid powder is prepared by drying an aqueous solution of said compound of quaternary ammonium to achieve a solid product and subsequently mixing at least one powder salt of a medium to long chain fatty acid with a multivalent counterion with said solid product in an amount of at least 0.1 parts by weight and less than 10 parts by weight, per 100 parts by weight of said quaternary ammonium compound, characterized in that before drying said aqueous solution, it is introduced into the same to at least one water soluble salt of a medium to long chain fatty acid with a univalent counterion, at least 0.1 parts by weight and less than 10 parts by weight, of said water soluble salt in said aqueous solution, per 100 parts by weight of said quaternary ammonium compound.Un procedimiento para preparar un polvo fluido que contiene, en una base en peso seco, por 100 partes en peso del polvo, al menos 85 partes en peso, preferiblemente al menos 90 partes en peso y más preferiblemente al menos 95 partes en peso de al menos un compuesto de amonio cuaternario delicuescente, en donde dicho compuesto de amonio cuaternario se selecciona del grupo que consiste en betaína, especies de colina y cloruro y bromuro de tetrametilamonio, y en cuyo procedimiento el polvo fluido se prepara secando una solución acuosa de dicho compuesto de amonio cuaternario para conseguir un producto sólido y posteriormente mezclando al menos una sal pulverulenta de un ácido graso de cadena media a larga con un contraión multivalente con dicho producto só
