The effect of Fe-doping on the surface chemistry and gas-sensing properties of nanocrystalline tin oxide is analyzed. The pristine and Fe-doped SnO2 are synthesized by the modified Pechini citrate route that produces around 40 and 18 nm sized nanoparticles, respectively. 1 at.% Fe-doped SnO2 shows significantly high selectivity towards hydrogen sulfide gas with capability to detect even 10 ppm of hydrogen sulfide at room temperature, with change of about one order of magnitude in the resistance within 5-15 s. In comparison, pristine SnO2 shows negligible response towards H2S at room temperature. The ideal response and recovery of Fe-doped SnO2 at low concentration of gas suggests Fe-doped SnO2 nanomaterial as a potential low cost, low temperature H2S gas sensor. (C) 2007 Elsevier B.V. All rights reserved.