Sensitivity and response of metal oxide based gas sensors depend on various aspects including design as well as environmental parameters. This paper discusses the positioning of interdigitated electrodes (IDE) with respect to sensing film, for sensor response optimization. Two arrangements of IDE were considered, one with electrodes below the sensing film and other with electrodes above the sensing film; both schemes were further characterized for ammonia sensing, at different temperatures. Tin-oxide (SnO2) film was used as the sensing film to discern the gas sensing behavior of the two schemes. The film was also characterized by atomic force microscopy and UV-visible spectroscopy. The scheme with electrodes on top of the sensing film, showed about two times better response (∼2×) than the other case, when examined in the presence of 10 ppm ammonia (NH3). The same was earlier validated by the simulations performed using COMSOL. Electrodes on top configuration has shown improved response for hydrogen sulphide (H2S) as well. © 2018 IOP Publishing Ltd.