Secondary ion mass spectroscopy (SIMS) provides a method to examine the 3D distribution of chemical elements in solids. We created a software program (Visualizer) for the visualization of SIMS 3D data using the visualization toolkit (VTK), a free C++ class library for 3D graphics. Furthermore, we used fusion in order to obtain one single image from several 3D images, each showing the 3D distribution of one chemical element within the sample.