An apparatus and method for preparing and dispensing a liquid deicer. The apparatus and method allow deicer ingredients or precursors to be combined in an exothermic reaction to produce a heated deicer at the location where it will be used. In one implementation, potassium hydroxide and acetic acid are combined using the apparatus and method to make hot potassium acetate for use in numerous deicer applications, including deicing of airport runways.