Process for the preparation of water-soluble active substance concentrates, the crystals of an active substance being distributed homogeneously in a first organic solvent in an anhydrous process using solid active substances as starting material by adding a dispersing auxiliary agent, adjusting the viscosity if necessary of the solution thus obtained with a suitable auxiliary agent, adding a polymer former to the solution of this type obtained, if necessary in a second organic solvent, adjusting the viscosity of either the solution to be added or the solution obtained if necessary by the addition of a suitable auxiliary agent, and returning to the solution obtained a cross-linking agent with at least two functional groups in a third organic solvent, in turn adjusting the viscosity or of the solution to be added or of the solution obtained, if necessary, by the addition of a suitable auxiliary agent, characterized in that the polymer former is selected from the group comprising low viscosity polymethylene polyphenyl isocyanate, preferably with an average NCO content of 25-35, more preferably 30-32%, as well as mixtures thereof, and the crosslinking agent is an at least bifunctional crosslinker for NCO groups and is added in at least a stoichiometric amount, the crosslinking agent being or comprising an ethanolamine, especially triethanolamine (TEA).Procedimiento para la preparación de concentrados de sustancias activas solubles en agua, distribuyéndose homogéneamente los cristales de una sustancia activa en un primer disolvente orgánico en un procedimiento anhidro usando sustancias activas sólidas como material de partida añadiendo un agente auxiliar dispersante, ajustando dado el caso la viscosidad de la solución así obtenida con un agente auxiliar adecuado, añadiéndose un formador de polímeros a la solución de este tipo obtenida, dado el caso en un segundo disolvente orgánico, ajustándose la viscosidad o bien de la solución que va a añadirse o bien de la solución o
