This work describes the fabrication of poly(4-styrenesulfonic acid)-doped polyaniline/graphene (PSS-doped PANI/graphene) nanocomposites and their use as sensing elements for hydrogen sulfide (H₂S) detection. PSS with a weight average molecular weight (M_w) of 1.96×10⁶ was synthesized using low-temperature free-radical polymerization. The high M_w of PSS resulted in relatively large particle sizes and smooth surfaces of the PSS-doped PANI. These physical characteristics, in turn, resulted in low interparticle resistance and high conductivity. PSSdoped PANI/graphene composites containing 30-wt% graphene showed the highest conductivity (168.4 S cm^-1) and the lowest minimum detection level (MDL) for H₂S gas (1 ppm).