This study evaluated the application of a continuous-flow photocatalytic reactor for the control of two mobile-derived pollutants, methyl-tertiary butyl ether (MTBE) and naphthalene, present at in-vehicle levels. Variables tested for this study included the hydraulic diameter (HD), stream flow rate (SFR), relative humidity (RH), and feeding type (FT). The fixed parameters included contaminant concentration, ultraviolet light source, and the weight of TiO_2. In all experimental conditions the adsorption process reached equilibrium within 30 to 180 min for the target compounds, and the outlet concentrations of the photocatalytic oxidation (PCO) reactor while operating reached a steady state within 60 to 180 min. The degradation of the target compounds was dependent on RH, HD, FT, or SFR. The PCO system exhibited high degradation (up to nearly 100% for certain conditions) and mineralization efficiencies of target compounds, suggesting that this system can effectively be employed to improve indoor air quality. Moreover, it was confirmed that trichloroethylene at urban-ambient level also could enhance the degradation efficiency of naphthalene when applying the PCO technology inside vehicles.