Abstract: A continuous fermentor or reactor and process using the reactor for producing ethanol including at least two vertically arranged unit reactors each having an open top cone which is connected to an inverted open bottom cone by a short cylinder greater in diameter than the two cones. The lowest unit reactor is connected to a gas supply member and a liquid introducing pipe and the highest unit reactor is connected to a gas separator and a mash discharge pipe. Inert gas introduced into the bottom unit produces both upward and downward flows in each unit.