Abstract We report that NaOH hydrothermal treatment and HF post-treatment of the titanium mesh for the Pt/Ti counter electrode improved the efficiency of dye-sensitized solar cells. High performance platinum nanoparticles have been sprayed onto Ti meshes to form counter electrodes for use in large-area flexible DSSCs using a vacuum thermal decomposition method at low temperature (120°C). The obtained Pt/Ti counter electrode shows low charge-transfer resistance (57.52Ωcm2 with active area of 80cm2) and high electrocatalytic activity for the I3−/I− redox reaction. The photovoltaic properties and resistances of Pt/Ti counter electrodes with different HF post-treatment times of the NaOH treated Ti meshes have been investigated. The efficiency of the large-area (80cm2) flexible DSSC reaches 6.17% under irradiation with a natural light intensity of 55mWcm−2 measured outdoors.