An experimental focused H+2ion beam system being developed for use in a focused ion beam lithography application is described. The system uses a gaseous field ionization ion source operated at cyrogenic temperatures with a 〈100〉 thermal field built‐up tungsten emitter tip to confine the ion emission. A five element cylinder electrode lens is designed to focus the hydrogen ion beam. Modeling results show a 120 Å probe could be scanned over a 0.2 mm square field at 30 keV utilizing the high resolution ion optics that the gaseous field ion source permits. Initial ion optical results from this system are presented.