We develop a microionizer as the ion source in a miniaturized spectrometerlike gas analyzer, operating at atmospheric pressure. Several options for the ionizing principle were considered. The application of dc glow discharge in a microsystem was studied in detail and first devices were fabricated and tested. We obtained stable dc plasmas in micromachined electrode gaps from 1 to 50 mum width, at pressures up to 10(5) Pa in various gases. With 1 and 3 mum gaps, stable glow was achieved at atmospheric pressure in Ar and N-2, respectively. In a macrosystem, we extracted ions from a dc glow discharge and controlled the ion flow with a grid. (C) 2003 American Vacuum Society.