We report on the improved spatial resolution of the ANSTO heavy ion microprobe, achieved through the use of a higher brightness ion source for hydrogen. The improved resolution will be demonstrated for applications of mu-PIXE. With the higher brightness source, a 3 mu m resolution was achieved for mu-PIXE elemental analysis. This is illustrated in high resolution images of nickel (Ni)-hyperaccumulating Hybanthus floribundus subsp. floribundus leaf tissues, where individual cells were clearly visible in the acquired elemental images. The higher resolution images illustrated that Ni was localised in epidermal cell walls. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.