Doping is a notable factor to improve the performance of CdTe/CdS heterojunction solar cell. Graphite doped CdTe/CdS heterojunction on Si (1 1 1) substrate has systematically fabricated by thermal evaporator method under medium vacuum (10 -4 torr) condition. Characterization of doped CdTe/CdS film was carried out by various diagnostic techniques such as X-ray diffraction (XRD) exhibits the polycrystalline structure of cubic phase CdTe and hexagonal phase CdS, scanning electron microscopy (SEM) shows the smoothening of the film, energy dispersive X-ray (EDX) confirm the elemental composition found in the film and current-voltage (I-V) analysis suggests the diode like properties where the current is slightly increased by the doping of graphite into CdTe/CdS heterojunction compared to the reported literature. Analysis of I-V characteristics has been made to investigate the current conduction mechanism in CdTe/CdS heterojunction.