The electrostatic effect constants for the substituents in an aromatic system were used firstly to study the bond dissociation enthalpy (BDE) of a halomethane system Y-CH_nX_{3-n (n＝0, 1, 2; 3; Y＝H, F, Cl, Br and I; X＝F, Cl, Br and I). Four parameters, the average bond energy of bond Y—C in the halomethane molecules, the sums of the field/induction effect ΣFi and the conjugated effect ΣRi of the groups (or atoms) binding with the carbon atom of the radical •CHnX3－n, and the sum of the induced dipole Σ(α×F), were employed, and a general model was obtained for estimating BDE of Y—C bond in the molecule Y-CHnX3－n: BDE(Y—C)＝57.5460＋0.8855 －101.0780ΣRi－64.8390ΣFi－10.1034Σ(α×F). For the 35 Y—C bonds, the estimating error using the above model is within the experimental error bars. The predictive ability of the model was tested by the external data sets, and the predicted results showed that the model had a good prediction accuracy (the root square error was 6.77 kJ/mol). Thus, the model can be employed with confidence to predict the BDE for the Y—C bonds in Y-CHnX3－n whose experimental values are unavailable yet. The BDE values of other 104 Y—C bonds were predicted and tabulated. The present method provides a new avenue to study the BDE of the saturated system with the electrostatic effect constants for the substituents in an aromatic system, and it is helpful to understand the effect of substituent electrostatic effects on the property of a chemical bond.}

Key words: substituent, electrostatic effect, halomethane, bond dissociation enthalpy