Betaine aldehyde dehydrogenase from Arthrobacter globiformis was purified to apparent homogeneity by ammonium sulfate fractionation, followed by ion-exchange, butyl-Toyopearl and gel filtration chromatography. The enzyme was found to be a tetramer with identical 55 kDa sub-units. Both NAD(+) and NADP(+) could be used as a cofactor for the enzyme and Michaelis constants (K-m value) for NAD(+) and NADP(+) were 1075 muM and 48 muM, respectively. The enzyme was highly specific for betaine aldehyde and the K-m value for betaine aldehyde was 36 muM.