A combined diagnostics and modelling of low pressure H2/O2 plasmas at different pressures and mixture ratios, generated in a low pressure hollow cathode DC reactor, is presented. Neutral and ion distributions are measured by mass spectrometry. Langmuir probes provide charge densities and electron temperatures. As expected, apart from the precursors, H2O is detected in considerable amounts and H3O+ is a major ion for H-rich mixtures. A zero order kinetic model is used to explain the experimental results. H2O is produced via plasma-surface interactions in a multistep process. The ion distributions are determined in each case by a balance between the relative weights of electron impact processes and proton transfer chemistry.N
