Herein we investigated the photoelectrochemical performance of manganese (Mn) doped cadmium sulfide (CdS) quantum dots (QDs) decorated onto the surface of hierarchical double-layered rosette-rod titanium dioxide (TiO2) photoanode. The rosette-rod TiO2 architectures are synthesized by two steps hydrothermal process while Mn-doped CdS QDs deposition is taken out by successive ionic layer adsorption and reaction (SILAR) approach. Two different kinds of structures exist simultaneously in rosette-rod TiO2, one-dimensional TiO2 nanorod arrays present at the bottom, while the upper three-dimensional nano rosette consists of small TiO2 nanorods as building units. Photoelectrochemical performance of the as-prepared photoanodes are explored in terms of photocurrent density and applied biased to photon conversion efficiency by varying Mn concentration and the number of SILAR cycles to find the best performing photoanodes. Linear sweep voltammetry results show that 35 mM shows the maximum photo-current density of 2.12 mA cm(-2) at 1.23 VRHE with a maximum photoconversion efficiency of ~ 1.61% at 0.4 VRHE, while 8 numbers of SILAR cycles shows the highest photo current-density of 2.73 mA cm(-2) at 1.23 VRHE and maximum photoconversion efficiency of 2.19% at 0.2 V-RHE.