x-ray fluorescence spectroscopy (XRF) has been demonstrated to have the ability to rapidly and directly measure sodium in a variety of cheeses by Stankey et al. Their rapid and simple method used a disk of cheese as the sample. However, inaccuracies may result from the formation of a thin layer of butter oil forming between the cheese and the surface of the holder and from using cheese samples that do not have a uniform surface such as shredded or ground cheeses. It is also important in process cheese manufacture to control the concentration of chloride, phosphorus and potassium as well as sodium. This study investigated various modifications to the sample preparation procedures for XRF technology that would remove the mentioned limitations, expand the minerals assayed, and evaluate the feasibility of using XRF in a manufacturing situation. The optimum sample preparation was created by homogenizing process cheese into 0.1 N nitric acid at 50o C. The homogenate was then centrifuged for 2 min in a microcentrifuge to separate the sample into a solids, an aqueous, and an oil layer. Two to 3 mL of the aqueous layer was removed from the centrifuge tube and assayed in an Oxford Instruments X-Supreme8000 Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometer. Instrument assay time was 3 min, which allowed simultaneous measurement of the minerals of interest. Total time from sample submission to result was 15 min, making it rapid enough for in-plant quality control use. Relative standard deviation for multiple trials with the same block of process cheese product was 3.0% for sodium, 6.5% for phosphorus, 0.9% for chlorine, and 1.4% for potassium in preliminary studies. The instrument calibration to a reference ICP method has an R2 of 0.915 for sodium using a straight line fit. The modified XRF method extends the range of minerals assayed and addresses the causes of the inaccuracies that had limited the desirability for industrial use.