Pure and copper doped SnO₂ nanowires have been grown by thermal evaporation technique. The results show that Cu may be doped in SnO₂ nanowires in contrast to results reported for thin films and polycrystalline materials. H₂S gas sensors have been fabricated from single wires and drop cast films prepared using the nanowires. It is seen that pure SnO₂ single wire sensors have better response for H₂S in comparison to doped films and in contrast drop cast films show improved response on doping. Results show that changes at barrier height between nanowires are responsible for the very high response of drop cast Cu doped nanowire films.