A new method to calibrate the binding energy (EB) using Au nanocolloids as a calibrant in XPS analysis of diamondlike carbon (DLC) is proposed by considering the DLC films with different electrical resistivities. A few microliters of a dilute aqueous solution containing Au nanocolloids were dropped onto a small local surface area of the DLC film, which became a stain before XPS measurements by gradually drying in vacuo. The observed peak EB of the C 1s spectrum at another native surface (an area without Au nanocolloids) of the DLC film was calibrated by setting that of the Au 4f(7/2) spectrum of the Au nanocolloids to 84.0 ( 83.98 +/- 0.02) eV. The adequacy of this method was investigated by considering the correlation among the full width at half maximums (FWHMs) of the Au 4f(7/2) spectra of the Au nanocolloids on the DLC surfaces and that of a Au plate as a reference. Consequently, the FWHM of the Au 4f(7/2) spectrum of the Au nanocolloids on the DLC surface is a candidate to investigate the differential charging effect of the DLC surface, and the calibration method is reliable if the FWHM agrees with that of the Au plate. (C) 2007 Elsevier B. V. All rights reserved.