A highly reproducible photoresponse is observed in nanocrystalline SnO₂ thick films sensitized with CdSe quantum dots. The effect of the SnO₂ matrix microstructure on the photoconductivity kinetics and photoresponse amplitude is demonstrated. The photoresponse of the sensitized SnO₂ thick films reaches more than two orders of magnitude under illumination with the wavelength of the excitonic transition of the quantum dots. Long-term photoconductivity kinetics and photoresponse dependence on illumination intensity reveal power-law behavior inherent to the disordered nature of SnO₂. The photoconductivity of the samples rises with the coarsening of the granular structure of the SnO₂ matrix. At the saturation region, the photoresponse amplitude remains stable under 10⁴ pulses of illumination switching, demonstrating a remarkably high stability.