Acetobacter acetii DSMZ3508 and related bacteria converted 2,2-dimethyl-1,3-propanediol into 3-hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid; 3HP) during submerged cultivation in mineral salt medium, The maximum yield of 3-hydroxypivalic : acid was 24.4% of the fed substrate after 18 days. Cultivation parameters, as pH, cell density, optimal substrate concentration, and oxygen supply for the bioconversion process were determined.