ZnO nanoparticles and ZnO/CdS Core/Shell heterostructures have been prepared in the two-step hydrothermal method by using Starch as a capping agent. The tunability of the optoelectronic properties of ZnO/CdS can enhance the exciton life time. These type of Core/Shell nanostructures are coming under Type-II band alignment. The thickness of the shell CdS is varied, keeping the core ZnO nanopins are in the same sizes. The absorption and luminescence properties of ZnO/CdS Core/Shells are well studied. The longer exciton life time of these Type-II Core/Shell nanostructure could be beneficial for the potential application in Photosensor.