A variety of surface analytical tools are available to the process engineer, but data from these tools may be misleading because of hidden pitfalls in the surface analysis technique. Examples from x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), total reflection x-ray fluorescence (TXRF), and atomic force microscopy (AFM) are used to illustrate some of the problems encountered when interpreting data from surface analysis equipment. Suggestions are made to assist users of these techniques in avoiding these pitfalls.