This method is for determining trace metal elements in fresh, regenerated and spent alumina-, silica- or silica/alumina-based catalysts by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Fe, Ni, V, Ca, Mg, Mn, Cr, Sn, Cu, Zn, Ti, Pb, Na, Mo, Co and Si are determined quantitatively on catalysts. Si is not determined when it is a component of the catalyst base. Other elements can be added if required, however, Ba and Hg cannot be determined. In addition, As and P are determined on regenerated or spent alumina-based catalyst. The majority of the specified elements can be determined within the concentration range of 0.005 to 2.0 mass-%. Specific concentration ranges for the elements determined are listed in Table 1. This method is not applicable to noble metals and modifiers on catalysts. Those elements can be determined by UOP Method 873. This method cannot be used for determining impurities in alpha-alumina catalyst.