Abstract: A method for creating ultra-fine particles of material using a high-pressure mill is described. The method includes placing a material in a first chamber and subjecting the material to a high-pressure liquid jet to divide it into particles. These particles are then transferred to a second chamber in which they are subjected to cavitation to further divide the particles into relatively smaller particles. These relatively smaller particles are then transferred to a third chamber, in which the particles collide with a collider to still further divide them into ultra-fine particles of the material. The mill of the present invention includes a first chamber having an high-pressure liquid jet nozzle, first and second slurry nozzles, a second cavitation chamber and a third chamber which houses a collider. Sensors may be located throughout the mill to collect data on the comminution process and to use the data to control the resultant particle size.