Mesoporous single crystals are prized for their fast electron transport and high surface area. Here we report the first synthesis of mesoporous SnO 2 single crystals (SnO 2 MSCs) by a simple silica-templated hydrothermal method, and its application in solution-processed perovskite solar cells (PSCs). A relatively low efficiency (3.76%) was obtained due to the strong charge recombination at the SnO 2 /perovskite interface. However, by coating a thin TiO 2 barrier layer on SnO 2 via TiCl 4 treatment, we were able to achieve an 8.54% power conversion efficiency (PCE). A dynamics study using impedance spectroscopy revealed a much lower transport resistance for the SnO 2 MSC-based solar cells than for the TiO 2 nanocrystal PSCs, but a stronger recombination. Significantly, the thin TiO 2 coating layer on SnO 2 considerably reduced the recombination while largely maintaining the superior electron-transport properties. © 2015 the Owner Societies.