The ternary MoBi2S5 and quaternary MoBiInS5 thin films were successfully synthesized by self organized APT at relatively low temperature. The tuning in band gap from 1.0 eV to 1.5 eV is due to the quantum size effect. This is beneficial for solar cell applications. XRD of MoxBi(3-x)S5 ternary thin film confirms the nanocrystlline nature but its crystallinity increases with [In]/[Bi] molar ratio in MoBi(2-x)InxS5 thin films. EDS and XPS studies showed good agreement in experimental and theoretical composition of APT grown thin films. Annealing and surfactant-assisted process is effective for improved in the optostructural, morphological and electrical properties of ternary and quaternary thin films. PEC cell performance is studied for both ternary MoxBi(3-x)S5 and quaternary MoBi(2-x)InxS5 thin film photoelectrode. It is seen that MoBiInS5 photoelectrode shows better conversion efficiency (¿~0.34 %). The PEC performance enhanced by addition of surfactants and also improved by annealing. It is found that the annealed MoBiInS5 -473 thin film displays maximum power conversion efficiency (¿) 0.49 %.