Correlation analysis of the standard Gibbs energy for a series of tetraalkylammonium ions, protonated substituted ethylenediamine derivatives and protonated aromatic amine derivatives using three new topological indices Ax1, Ax2 and Ax has been studied. The regression equations of the standard Gibbs energy were obtained. The correlation coefficients between the Gibbs energy and the topological indices were 0.9851, 0.9939 and 0.9301 respectively. The values of the Gibbs energy calculated using this method were in good agreement with the values determined electrochemically.