PbS x Se 1-x alloys with different S content (0,0.1,0.15,0.3,0.4,1) have been successfully prepared by evacuated quartz tube under vacuum pressure (10 -2 Toor). PbS x Se 1-x thin films have been prepared by thermal evaporation technique on glass substrate at room temperature (RT) under vacuum pressure 10 -5 mbar at deposition rate 5nm/sec .The effect of S content on some of the electrical properties has been studied.The structure of (PbS x Se 1-x ) alloys and films have been studied by X-ray diffraction technique. X-ray diffraction study shows that the Structure is polycrystalline with cubic Structure with preferential orientation in the (200) direction for films. From D.C measurements all films have shown two activation energies, the first at low temperature for activation energy E a2 and the second at high temperature for activation energy E a1 ,where these value decreases with increasing S content. And it is found that D.C conductivity decreased with increasing S content, while activation energy increases with increasing S content.. From the Hall measurement, the films of (X=0,0.1,0.15,0.3,0.4) are n-type and the films of (X=1) are p-type. Also the results showed that the carriers concentration decreases with increasing S content, but the Hall mobility µ H increased, and the value of R H ) decreased with increasing S content.