The determination of aluminium-to-silicon ratios in zeolites is of great benefit to catalyst technology and of general interest to mineralogists. However, such determinations tend to be open to error because of interferences that are due mainly to the juxtaposition of these elements in the Periodic Table. The capabilities of neutron activation, both with isotopic sources and accelerator based, of PIXE and of XRF were evaluated to establish which of these instrumental methods was best suited especially for routine on-line usage.