Abstract: According to the invention, there are provided improved apparatus and process for preparing high temperature reaction products in an electric furnace. Into the furnace, a combustible material and an oxygen-containing gas are fed by means of a suction-type water-cooled lance. The discharge end of the lance in the furnace is opened at a specific position within the unreacted material deposition zone in the furnace so that incomplete combustion is effected, thereby producing useful by-product gases. Cooling water is recirculated by a suction pump interposed at a position downstream of the lance outlet.