Glutamate and glutamine were determined by lummol chemilummescence with flow-injection analysis (FIA) based on immobilized L-glutamate oxidase and glutaminase coupled with peroxidase The laboratory-made flowthrough cell of the detector has a measured volume of only 15 jA The hydrogen peroxide produced in the first reaction is detected by lummol chemilummescence catalysed by peroxidase A membrane sensor and enzyme reactor based on immobilized hydrogen peroxidase are used for the determination of hydrogen peroxide It was observed that Arthromyces ramosus peroxidase produced a 100 times stronger luminescence signal than horseradish peroxidase By immobilization of the microbial peroxidase on a membrane inside the flow cell, simplification could be achieved with regard to apparatus, reagents and operation The sensitivity of detection was considerably improved In addition, the concept of a hydrogen peroxide biosensor was realized The membrane sensor shows a detection limit of 1 x 10 -7 M for L-glutamate and 1 x 10 -6 M for L-glutamine The calibration graphs were approximately linear in the range of 1 x 10 -7-6 x 10 -5 M for L-glutamate and 1 x 10 -6-2 5 x 10 -3 M for L-glutamine The membrane sensor was stable over a period of 10 weeks (> 1000 analyses)