Expert Systems (ES) can guide users in application of XPS.@footnote 1-6@ Guidance requires modules of the ES to be tailored to a particular group, e.g., corrosion scientists. This group, which has defined needs and a history of using XPS, could benefit from automated knowledge retrieval. In creating a set of rules, the requirements are defined and matched to the information that might be delivered by XPS, e.g.: the mean surface composition and relation to the bulk; the location of any marker elements; the thickness of overlayers, e.g., a contamination layer and an oxide or similar layer; evidence for graded composition such as enrichment of an alloying element in the oxide or metallic undersurface; valance states and a trial stoichiometric composition. Reminders of further opportunities should also be provided, possibly by use of on-screen wizards.@footnote 4,5@ In proposing this ES module emphasis will be placed on the cost-effective provision of basic information from the 'survey scan'. The rules have provenance from prior discussion and publication by international workshops such as those sponsored by IUVSTA.@footnote 1,3,6@ The rule base will be most useful when it is embedded in the controlling system for the spectrometer, so that some degree of knowledge based acquisition is possible, but would be equally suitable for stand alone, retrospective analysis. Both outcomes make a demand on costly resources that in the end will have to be provided by the user community. It is hoped that this feasibility study will show that, for corrosion scientists, this is worthwhile. @FootnoteText@ @footnote 1@M-G Barthes-Labrousse, Surf.Interface Anal. 26 p72 - 91 (1998) @footnote 2@J.E.Castle and M.A.Baker, J. Elec Spec & Rel. Phenom., 105 p245 - 256 (1999) @footnote 3@L.Kover, Surf. Interface Anal. 29 p671 - 716 (2000) @footnote 4@J. E. Castle, PV 2001 - 5, C.R.Clayton et al. Eds. The Electrochemical Soc., NJ. pp1-14(2001) @footnote 5@J.E.Castle, Surf.Interface Anal. 33 pp 196 - 202 (2002) @footnote 6@ Report of St Malo Workshop, to be pub.