Abstract: Four-carbon dicarboxylic acids are important group of additives with a number of industrial applications. Tartaric acid belongs to the group of organic acids which have many applications mainly in beverages and food industry. The ability of bacteria Rhodococcus sp. to produce L-tartaric acid from cis-epoxysuccinic acid was investigated under various conditions. The addition of cis-epoxysuccinate to the medium was necessary to enhance the activity of key´s enzyme. Pretreatment of the cells with glutaraldehyde or polyethylene imine had no significant permeabilizing effect on bacterial cells. The highest activity and stability of CEH in three repeated bioconversions by intact cells were achieved after cell´s treatment by sodium deoxycholate (0.2 g/l) with a duration of 15 minutes.