The Fe2O3 and CoFe2O4 nanoparticle-based Langmuir–Blodgett films for sensing of nitric dioxide (NO2) and acetone vapours have been explored. Both the sensitivity of the chemiresistors and dynamic properties, such as the response/recovery time, have been probed in dependence of the number of nanoparticle monolayers and working temperatures. The response of 23 at the NO2 concentration of 1 ppm, i.e., approaching the canine detection limit, has been monitored implying the appropriateness for the detection of nitrate-based explosives.