Development of nanostructure gas sensing materials is gaining considerable attention at present times. In this light, the present article reports on the synthesis and detailed characterization of nanocrystalline lead sulplide (PbS) as gas sensors. Sol-gel technique was used in preparing undoped PbS nanocrystalline material at two different reaction temperatures (60 degrees C and 90 degrees C) and was characterized by x-ray diffraction (XRD) as well as scanning electron microscopy (SEM). Results of XRD showed respective crystallite sizes of 17.81 nm and 14.5 nm. Synthesized PbS materials on SEM analysis further showed agglomerated crystalline structure. Response of these materials was studied in presence of water vapors as well as various other gases and vapors of organic solvents at various temperatures (25 degrees C to 90 degrees C). The gas sensing behavior showed that the synthesized nanocrystalline materials were influenced predominantly by NH3 and NO2 amongst many other gases at room temperature.