MOVPE has become the main industrial technology for the preparation of modern electronic (HEMTs for mobile communication, navigation and location) as well as optoelectronic (lasers, LEDs, detectors or solar cells). Now a new generation of digital mass flow controllers is described, claimed as ideally suitable for fast, accurate and stable precursor supply into an MOVPE reactor. The instruments are capable of handling typical precursor flow rates of the order of (gases) 5 slm AsH3, PH3 and NH3 and (liquids) 50 g/h TMA, TMG and TMI. The settling time t 98% of the instruments is 200μs and 2μs, respectively.