AbstractA multivariate QSAR for estimating the ionization potential (IP) of halo‐alkanes has been constructed. 69 compounds, including 47 for which experimental IP data in the 10 to 13.6 eV were available were parametrized with 12 structural descriptors. The data analysis to correlate IP to these descriptors was carried out by PLS that gave a tri‐dimensional model explaining over 80% of the variance of IP. The reliability of the model was evaluated on the basis of predictions by using two different approaches. These were (a) a modified PLS version providing the Standard Deviation of Errors of Prediction, the SDEP parameter, which was found to be +/− 0.45 eV, and (b) an “external” validation process where the standard deviation was computed on the basis of the predicted IP.s for 17 compounds kept outside the training set, and was found to be +/