The continuous pyrolysis of CANMET coprocessing residue in argon/hydrogen plasma was studied for the temperature range 2700 to 3670 K using an induction plasma torch. Hydrogen was injected into the argon plasma tailflame at molar concentrations ranging from 0 to 23%. The residue was continuously fed in liquid form to a laboratory-scale reactor specially built for the study. The residue flow rate ranged from 6 to 9 g/min. A maximum of 10% of the residue pyrolysed with up to 90% conversion to gaseous hydrocarbons. The rate of residue pyrolysis and the rate of formation of the gaseous products were found to be strongly dependent on the rate of heat transfer at the residue surface. The only gaseous products detected were acetylene, ethylene and methane. Some soot was produced, but no liquid hydrocarbons were detected.