Alanine dehydrogenase from the hyperthermophilic archaeon Archaeoglobus fulgidus was used at room temperature for batch synthesis of L-alanine by the reductive amination of pyruvate. The reaction mixture included yeast formate dehydrogenase for regeneration of NADH with formate as electron donor. The synthesis of L-alanine at room temperature was accompanied by no detectable loss of alanine dehydrogenase activity over 139 h and :99% consumption of pyruvate. The total number of enzyme turnovers was 5.1 million. This work demonstrates the potential utility of novel hyperthermostable enzymes that can be both very active and highly stable at moderate temperature.