Total reflection x-ray fluorescence (TXRF) spectroscopy is used during process development and production process monitoring. Instruments used for these applications require measurement calibration and reproducibility. During 1994, a set of Ni dosed silicon wafers (approximately 1 x 10(11) atoms/cm(2)) was fabricated and used in a "spoke in wheel" type of analysis round-robin. In this case, a set of samples was fabricated, analyzed by TXRF, and then smaller sets of three wafers were sent to five individual laboratories for analysis. The TXRF data demonstrated the reproducibility of TXRF results when samples have a uniform distribution across the surface. This work also points to the need for reference materials less than or equal to 1 x 10(10) atoms/cm(2). Gupta has previously shown that vapor phase decomposition (VPD) of Ni contamination is difficult, and we also report on VPD analysis of Ni [Gupta et al., Electro-Chem. Sec. Proc. 94-9, 200 (1994)]. We discuss the reproducibility of TXRF analysis of nonuniform surface contamination.