In this investigation, the effect of concentration of TiCl 4 for the post-treatment of hydrothermally synthesized titania nanotubes-based working electrode for dyesensitized solar cells has been studied. Hydrothermally synthesized TiO 2 nanotubes were treated with different concentrations of TiCl 4 to investigate the effect of TiCl 4 concentration. The solar cell performance increased with the increase in TiCl 4 concentration up to 0.5 M and leveled off. The best solar cell showed a short-circuit current density (J sc ), open-circuit voltage (V oc ), fill factor (FF) and efficiency (g) of 12.75 mA/cm 2 , 795 mV, 69.2 % and 7.04 %, respectively, while untreated TiO 2 nanotube showed J sc , V oc , FF and g of 2.4 mA/cm 2 , 899 mV, 78.9 % and 1.7 %, respectively.