Secondary alcohol ethoxylate (SAE) was photocataiytically degraded using a suspension of TiO2 particles irradiated with long wavelength ultraviolet light. High starting concentrations of SAE were used (ca. 2000 mg/L), and changes in both SAE oligomer distribution and production of intermediates were monitored by using GC, GC/MS, NMR, and ESMS. Initial preferential cleavage of the ethoxyl groups over HO* reactions with the aliphatic portions of the molecule is followed by cleavage at the secondary carbon. Relatively hydrophilic intermediates remained in solution, while the hydrophobic products adhered to the TiO2, causing agglomeration of the particles.