A newly-isolated strain of Serratia marcescens, G12, was characterized for 2,3-butanediol (2,3-BD) production. In shake-flask and batch fermentations, 2,3-BD reached 48.5 and 51 g l(-1), respectively. Low amounts of (similar to 8 g l(-1)) of acetoin were also formed. In fed-batch fermentations, strain G12 produced 72.8 g 2,3-BD l(-1) with glucose initially at 130 g l(-1). When aeration rate was increased to 2.5 vvm for the fermentation process, 2,3-BD reached 87.8 g l(-1) and the highest productivity was 1.6 g l(-1) h(-1). Acetoin was at 6.2 g l(-1). G12 therefore may be a suitable candidate strain for large-scale production of 2,3-BD.