This method is for determining trace metals in fresh, regenerated and spent alumina-, silica-, or aluminosilicate- (silica/alumina-) based catalysts by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES). Ordinarily, the metals determined include calcium (Ca), chromium (Cr), cobalt Co), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), potassium (K), silicon (Si), sodium (Na), tin (Sn), titanium (Ti), vanadium (V), and zinc (Zn). Silicon is not determined when it is a component of the catalyst base. Arsenic (As) and phosphorous (P) can be determined but are not ordinarily present on fresh catalysts. They may, however, be present on regenerated or spent catalyst. Barium (Ba) and mercury (Hg) cannot be determined because barium sulfate precipitates and mercury volatilizes. Barium can be determined using the fusion technique described in UOP Method 926, “Silicon and Aluminum in Fresh Catalysts by Lithium Tetraborate Fusion/ ICP-OES.” Other elements also can be determined, if required. The specified elements can be determined within the concentration anges listed in Table 1. Typical concentration ranges are 0.005-1.0 mass-%.