This paper examines how variables that influence photocatalytic events at ultraviolet (UV)-irradiated TiO2 particles manifest in the transient response from a slurry photoelectrochemical (PEC) cell. These include the nature of the ambient gas, electrolyte pH and composition, and the presence of hole accepters in the electrolyte. Unlike the composite photocurrent response observed in previous studies on TiO2-based slurry PEC cells, the photoresponse was almost exclusively anodic under the conditions extant in this work. The highest photoresponse was obtained in neutral electrolytes. Both O-2 and Cl- exerted a complex effect on the photoresponse, depending on the magnitude of the collector-electrode potential. Pulsed photoexcitation of the TiO2 particles enables decoupling of processes with variant time constants in the slurry PEC cell, such as O-2 adsorption on TiO2, adsorption of TiO2 particles on the collector-electrode surface, and mass transport of TiO2 particles to the collector electrode. Finally, the influence of three types of environmental pollutants : viz., organic (formaldehyde), inorganic [As (III)], and biological (Escherichia coli), on the slurry cell photoresponse, is discussed.