The purpose of the present study was to investigate the effect of the various types and amounts of polyethylene glycols on the potassium chloride release from wax matrices. Potassium chloride as a highly water-soluble model drug was embedded into wax containing surfactants to produce sustained release dosage form. Various kinds of polyethylene glycols were chosen to control the dissolution profile. The dissolution profile of the matrix samples was characterized by the Weibull distribution. The physico-chemical characteristics--surface tension, HLB value, refractive index--of the aqueous solutions of the polyethylene glycols were also determined. On the basis of the examined physicochemical characteristics of various polyethylene glycols it is possible to select the optimal concentration of surfactant to formulate matrix dosage forms of required dissolution profile.