[en] Electron cyclotron resonance (ECR) plasma generation by microwave injection in suitable magnetic field structures is widespread now due to some major advantages: low power consumption (if permanent magnets are used), no electrodes in plasma chamber, low gas loading of the vacuum system. Choosing a particular magnetic field arrangement in a hydrogen ECR discharge, a significant negative-ion output can be observed. An experimental set-up for mass spectrometric investigation of an ECR hydrogen plasma is presented. The influence of discharge parameters (pressure, microwave power, magnetic field configuration, plasma chamber wall material) on the negative ion current was investigated. (Author)