The instant invention relates to a process for controlling the viscosity of organic liquids by incorporating in said liquid a minor amount of an ionic polymer, and a cosolvent for the ionic groups of said polymer. The ionic polymer comprises a backbone which is substantially soluble in said organic liquid, and pendant ionic groups which are substantially insoluble in said organic liquid. A cosolvent is selected which will solubilize the pendant ionomeric groups and provide a reasonably homogeneous mixture of solvent, cosolvent and ionomeric polymer. The preferred compositions prepared by the method of the instant invention comprise an organic liquid having a solubility parameter of from 6 to 10.5 in combination with a sulfonated polymer containing from 0.2 up to 10.0 mole % ionic groups which has been neutralized by a basic material selected from Groups IA and IIA, IB and IIB of the Periodic Table of the Elements (and also lead, tin and antimony) and a nonvolatile alcohol or amine cosolvent.