A novel method for shortening the synthesis time of mesoporous TiO2 to 6 h is reported. Low-angle XRD and TEM showed that mesoporous TiO2 with short-range ordered structures was synthesized when octadecylamine was used as a structure-directing agent and when Ti(OPri)4 was used as a precursor. The highest surface area (853 m2 g-1) was obtained after extraction with a dilute solution of nitric acid. The material maintained a high surface area (467 m2 g-1) after calcination at 350 °C, but the short-range ordered structures collapsed. XPS showed the interaction between TiO2 and octadecylamine, while DSC, TGA, and FT-IR spectra showed the removal of octadecylamine by extraction and calcination. A mechanism for the fast formation of mesoporous TiO2 is proposed. It is attributed to the formation of mesoporous material at high temperatures formed in the interface between the gas and bulk solutions resulting from ultrasound irradiation. Electrodes made from the mesoporous TiO2 were tested in a dye-sensitized solar cell. The short-circuit photocurrent, open-circuit photovoltage and fill factor increased with an increase in the sintering temperature, having a performance threshold at 450°C, showing that the more ordered structures are required for high solar cell conversion efficiencies.