Polyaniline, which was obtained as a dispersion from a commercial supplier, was used to prepare chemo-resistors. The sensors were prepared in a batch process by spin coating on a wafer with Au interdigitated electrode arrays (IDAs). The gas response behaviour of the so-prepared sensors could be modified by a post-treatment with organic solvents to obtain an array of sufficiently different sensors for the successful recognition of five different vapours. The preliminary fabrication procedure showed a good batch-to-batch reproducibility, as well as an excellent stability of the sensor responses.