A method of melting materials at power densities in excess of 25 KW/ft² of area within the metal shell (11) of a melting vessel (10) which method comprises continuously feeding (13) the material to be melted to a plasma arc furnace, melting the said feedstock material using at least two transferred arc plasma electrodes (15,16) whilst rotating at least the portion of the furnace containing the material to be melted and continuously discharging the molten material through the rotating bottom (17) of the furnace. Apparatus for melting materials under power densities of greater than 25 KW/ft² is also disclosed.