Dodecyl benzene sulphonic acid (DBSA) doped polyaniline (PANI) nanorods have been synthesized by a templateless route via in-situ emulsion polymerization of aniline in aqueous DBSA solution. XRD patterns, UV-Visible Spectroscopy, and FTIR analysis confirm the formation of PANI and PANI-DBSA, whereas FESEM images revealed their elongated rod shaped morphology. The chloroform dispersion of synthesized PANI-DBSA was spin coated over prefabricated interdigitated Pt patterned glass substrate to realize porous gas sensing active layer. The sensor displays good response in 1-1200 ppm ammonia concentration range and can repeatedly detect 300 ppm of ammonia with response time of 6 s, recovery time of 37 s and relative response value of 9.57. Besides, its response was found to be linear for 1-50 ppm ammonia concentration with relative response per ppm value of 0.01675. © 2013 IEEE.