This study focus on investigating the oxidation potential fluctuation of organic molecule in the solution. The organic molecule that was investigated is 3-pentanone molecule that has oxi-dation potential 0.143 V experimentally. The oxidation potential was calculated using Born-Haber cycle approximation involving the calculation of gas phase Gibbs free energy and solvation energy of reduced and the oxidized state. The reduced state represents a neutral charge molecule and the oxidized state represents a radical cation molecule. The first, molecular dynamics (MD) simulation of both state was performed for 2 ns time. Then, 400 snapshot structures of both state molecule was captured. Gas phase Gibbs free energy and solvation energy were calculated using MP2 theory with cc-pvdz basis set and the solvation effect was approached using Polarizable Continuum Model (PCM). Normal Hydrogen Electrode (NHE), that has redox potential 4.44 V experimentally, was used as reference electrode. The result shows the different of gas phase Gibbs free energy average of both state was 756.97 ± 21.598 kJ/mol, and solvation energy average of reduced and oxidized state were -18.42 kJ/mol ± 1.482 kJ/mol, and -219.02 ± 1.094 kJ/mol respectively. Then, the oxidation potential was calculated by substituting gas phase Gibbs free energy and solvation energy into Born-Haber cycle approximation. The calculation result shows the average of oxidation po-tential value is 1.396 ± 0.225 V. The deviation of oxidation potential confirms the fluctuation of oxidation potential during the simulation
