Digital image holographic interferometry has been used to measure the mass diffusion coefficient of fluids. The mass diffusion coefficients of KCl in aqueous solution at a concentration pf 0.33 mol.dm(-3) as the standard solution was used to verify the precision and reliability of the apparatus. The results show that the absolute average relative deviations is within 1.20%. The uncertainty in mass diffusion coefficient is estimated to be not greater than +/- 0.2%. The mass diffusion coefficients of three different oxygenated fuel additives, bis(2-methoxyethyl)-ether (diethylene glycol dimethyl ether, DGM), 1,2-dimethoxyethane (ethyleneglycol dimethyl ether, GDME), and ethanol, were determined in both diesel oil and heptane at temperatures between (276 and 333) K.