X-ray fluorescence spectroscopy (XRF) is a common analytical technique found in many laboratories. The instrumentation for this technique is rather large and does not lend itself to on-site examinations. Recent innovation in solid-state technology make portable instruments available that can be used outside the laboratory in museum galleries or at archaeological sites. The use of such an instrument, however, has practical limitations that are different from laboratory models. This study relates experience with an Innov-X Systems portable X-ray fluorescence spectrum analyzer and examines the practical limits of analysis done with that system. Selected glass, gold, and bronze objects from museum collections as well as standards and materials previously analysed using inductively coupled plasma mass spectroscopy with laser ablation (LA-ICP-MS) were used in these tests. This study was meant not to present the theoretical limitations of XRF but to document the practical concerns of on-site XRF testing.