The D-glucose or the L-lactate oxidases were copolymerized by glutaraldehyde with bovine albumin and mounted on an oxygen electrode to form an enzyme electrode. This enzyme electrode was mounted on a Lachat QuikChem((R)) 8000 flow injection analysis (FIA) system. With this system the glucose and the L-lactate is simultaneously measured in the concentration range 0 to 40 g/liter. The enzymatic films can be used continuously for three months, at a rate of one measurement every two minutes. The stability of the enzyme electrode is greater than one year when stored in the dry state at 4degreesC. This FIA system can be used for monitoring simultaneously the concentration of D-glucose and L-lactate in the bioprocessing industries.