We have studied the surface binding and photochemistry of several volatile organic compounds (VOCs) on Degussa P25 TiO₂, a substrate often used for the remediation of indoor air pollution. The molecules examined included acetone, a common pollutant in indoor air, and intermediates proposed in its mineralization on TiO₂. Chemical ionization mass spectrometry (CIMS) was used to track the adsorption of acetone, formic acid, acetic acid, mesityl oxide and diacetone alcohol as well as to monitor the gas phase products generated upon exposure of the adsorbed VOCs to UV light. Experiments were conducted using analyte partial pressures representative of those found in the indoor environment (1 x 10^-6 and 6 x 10^-6 Torr). The measured sticking coefficients were slightly lower for acetic acid and formic acid (10^-4 – 10^-5) than for the higher molecular weight compounds (10^-4 – 10^-3). These acids also yielded more CO₂ than the other VOCs after UV irradiation of TiO₂ which had been exposed to low analyte partial pressures. High sticking coefficients for mesityl oxide and diacetone alcohol indicated that these possible acetone condensation products may act as poisons for surface activity. However, surfaces exposed to these condensation products produced acetone upon their exposure to UV, demonstrating that the irreversible binding in dark conditions may not be of concern if the surface is periodically irradiated. These data suggest that remediation of acetone in the indoor air may be best accomplished by surfaces that favor formate and acetate as intermediates in acetone mineralization.