Thin films of bulk heterojunction blend Ni-PhthalocyanineTetrasulfonic acid tetrasodium salt and dpoly(3, 4-ethylenedioxythiophene) poly (styrenesulfonate) (NiPcTs:PEDOT: PSS) with different (PEDOT:PSS) concentrations (0.5, 1, 2)are prepared using spin coating technique with thickness 100 nm onglass and Si substrate. The X-Ray diffraction pattern of NiPcTspowder was studied and compared with NiPc powder, the patternshowed that the structure is a polycrystalline with monoclinic phase.XRD analysis of as-deposited (NiPcTs/PEDOT:PSS) thin filmsblends in dicated that the film appeared at(100), (102) inconcentrations (0.5, 1) and (100) in concentration (2). The grain sizeis increased with increasing (PEDOT:PSS) concentrations. FTIRmeasurements for these bulk heterojunction blend thin films alsocarried out in this work and gave good information about the bondsand their locations. Sensor measurements of Si/NiPcTS:PEDOT:PSSbulk heterojunctions blend thin films show a good sensitivity for NO2gas Compared to NH3gas. The NiPcTS/PEDOT:PSS gas sensordevice work at room temperature than high temperature for NO2 gasbut good sensitivity at100ºC for NH3 gas and sensor work moreeffectively in 0.5 concentration for both gases.