For substituted benzenes such as (p-F-C6H4-Z), Linderberg et al. [1] demonstrated the validity of an equation similar to: ΔCEBE ≈ κσ where ΔCEBE is the difference in core-electron binding energies (CEBEs) of the fluorinated carbon in p-F-C 6H4-Z and that in FC6H5, the parameter κ is a function of the type of reaction, and σ is the Hammett substituent (σ) constant. In this work, CEBEs of ring carbon atoms for a series of para disubstituted molecules p-F-C6H4-Z were first calculated using Density Functional Theory (DFT) with the scheme ΔEκS (PW86-PW91)/TZP+Cre1//HF/6-31G*. An average absolute deviation of 0.13 eV from experiment was obtained for the CEBEs. Then we performed a linear regression analysis in the form of Y = A+B*X for a plot of Hammett σP constants against calculated shifts ΔCEBEs (in eV) for the fluorinated carbon. The results were: A = -0.08 and B = 1.01, with correlation coefficient R = 0.973, standard deviation = 0.12, and P < 0.0001. The intercept A of the fitted line, close to zero, shows that the Hammett σP constant is proportional to the calculated ΔCEBEs. On the other hand, the slope B of the straight line gives an estimate of the parameter κ. Similar statistical correlations were obtained for the carbon atoms ortho and meta to the substituent Z. © 2005 Wiley Periodicals, Inc.1035509515Linderberg, B., Svensson, S., Malmquist, P.A., Basilier, E., Gelius, U., Siegbahn, K., (1976) Chem Phys Lett, 40, p. 175Hammett, L.P., (1937) J Am Chem Soc, 59, p. 96Chong, D.P., (1995) Chem Phys Lett, 232, p. 486Takahata, Y., Chong, D.P., (2003) J Electron Spectrosc Relat Phenom, 113, p. 69Perdew, J.P., Wang, Y., (1986) Phys Rev, B33, p. 8800Perdew, J.P., Kurth, S., (1998) Density Functional: Theory and Applications, , Joubert, D., Ed.Springer: BerlinChong, D.P., (1995) J Chem Phys, 103, p. 1842Casida, M.E., Daul, C.D., Goursot, A., Koester, A., Pettersson, L., Proynov, E., St-Amant, A., Vela, A., (1997) DeMon-KS, V. 3.4, , deMon Software, University of Montreal, Montreal, Canada, ADF program System, Releaase 2000.02, Scientific Computing & Modelling, AmsterdamChong, D.P., (2002) Reviews in Modern Quantum Chemist, p. 1106. , A Celebration of the Contributions of R.G. ParrSen K. D., Ed.World Scientific Publishing: Singapore(2000) ADF Program System, Releaase 2002.03, , Scientific Computing & Modelling NV, AmsterdamLinderberg, B., Svensson, S., Malmquist, P.A., Basilier, E., Gelius, U., Siegbahn, K., (1975) Institute of Physics Report, UUIP-910. , Uppsala University, DecMartin, Y.C., (1978) Quantitative Drug Design: A Critical Introduction, pp. 378-393. , Marcel Dekker: New York