Thin films of titanium dioxide (TiO2) have been deposited from methanolic titanyl acetylacetonate precursor solution onto the preheated amorphous and fluorine-doped tin oxide (F:SnO2)-coated glass substrates at optimized substrate temperature of 470 degrees C by a spray pyrolysis technique. The objective of the study is to investigate the effect of film thickness on the structural, optical and photoelectrochemical (PEC) properties of TiO2 thin films by varying the precursor concentration from 0.05M, at the interval of 0.025M, to 0.125M. X-ray diffraction shows that the films are polycrystalline with anatase phase having tetragonal crystal structure. Scanning electron microscopy reveals uniform and compact distribution of spherical clusters comprising nanoplatelets of size similar to 200-400 nm. The films are nearly stoichiometric as confirmed by energy-dispersive X-ray analysis. Atomic force microscopy study also reveals uniform distribution of grains of size similar to 180-370 nm. The films are transparent (with %T > 70) and film thickness varies over 162-758 nm range with increase in precursor concentration. The band gap energy varies from 3.31 to 3.36 eV. Thickness of the TiO2 films is shown to have an influence on the PEC performance and plays an important role in determining the efficiency of the PEC cell. The precursor concentration of 0.1M is optimized using PEC technique. Incident photon to current conversion efficiency of 71.24% is obtained for 600 nm thick TiO2 film.