Charging property of liquid inks is the key in determining the performance in liquid toning. Depending on the charge density and mobility of the toner particles and other charged species in the carrier liquid, the toned images can be formed quite differently. This report describes an approach to obtain the charging property of colloidal dispersions. By bring together the experimentally measured plate-out current, the numerical models are designed to automatically determine the charging characterization of the dispersions. A charge transport model is used in which no change in the charging of all the charged species due to the variation of external field is assumed. The applicability of this method is examined with the experimental data using both regular liquid inks and dispersions of only micelle particles.