Goethite ( alpha -FeOOH) is a common mineral constituent of suspended and bed sediments in aquatic environments. Many types of naturally-occurring organic molecules, including organic carboxylates, are known to sorb to its surface. Carboxylates should be susceptable to photo-oxidation. An experimental program was conducted with systems containing adsorbed films of oxalate, citrate, tartrate, glycolate, formate, maleate, fumarate, butanoate, and benzoate on Goethite, respectively. Photolytic effects were observed at pH 6. 5 and 5. 5.