Production of ethanol in a thermophilic bacterium can be achieved by transformation of the bacterium with a heterologous gene encoding pyruvate decarboxylase. The bacterium comprises native alcohol dehydrogenase function and does not comprise a gene encoding a functional lactate dehydrogenase. The bacterium may be grown at elevated temperatures to allow the ethanol to be conveniently removed in a vaporized form from the fermentation medium. Traditional mesophilic microorganisms are incapable of growth at the envisioned elevated temperatures.