For monosubstituted benzenes (Ph-Z), Linderberg et al. demonstrated the validity of the equation ΔCEBE ≈ κσ, where ΔCEBE is the difference between the core-electron binding energies (CEBE) of a specific carbon in monosubstituted benzene derivatives (Ph-Z) and that of unsubstituted benzene (Ph-H), k is related lo the reaction constant and σ is the experimental Hammett sigma constant CEBEs of carbon atoms for a series of Ph-Z were calculated using density functional theory (DFT) with the scheme ΔEks(PW86-PW91)/TZP+ Crel,//HF/6-31G *. An average absolute deviation of 0.15 eV was obtained with respect to observed values. A linear regression analysis of the form y = A + BX of a plot of, for instance, Hammett ωρ-constants against calculated ΔCEBEs (in eV) at para-carbon for n =11 produced a value of A = -0.1310 and B= 1.056 with a correlation coefficient R = 0.983, a standard deviation of 0.099 and a p-value <0.0001. Copyright ©; 2004 John Wiley & Sons, Ltd.182187191Lingderberg, B., Svensson, S., Malmquist, P.A., Basilier, E., Gelius, U., Siegbahn, K., (1976) Chem. Phys. Lett., 40, pp. 175-179Hammett, L.P., (1937) J. Am. Chem. Soc., 59, pp. 96-104Takahata, Y., Chong, D.P., (2003) J. Electron Spectrosc. Relat. Phenom., 133, pp. 69-76Perdew, J.P., Wang, Y., (1986) Phys. Rev. B, 33, pp. 8800-8824Perdew, J.P., Wang, Y., (1992) Phys. Rev., B45, pp. 13244-13249(2000) ADF Program System, Releaase 2000.02, , Scientific Computing and Modelling: AmsterdamJolly, W.L., Bomben, K.D., Eyermann, C.J., (1984) At. Data Nucl. Data Tables, 31, pp. 434-493Exner, O., (1978) Correlation Analysis in Chemistry: Recent Advances, pp. 439-540. , Chapman NB, Shorter J (eds). Plenum Press: New YorkJohnson, C.D., (1973) The Hammett Equation, p. 93. , Cambridge University Press: Cambridge