Thin films of polypyrrole (PPY), doped with different counter-ions and prepared by in situ polymerization on conducting glass electrodes, are used for the development of gas sensors with fast response time. On exposure to a given vapor, each individual film exhibits a fast change of the fractional difference of its electrical resistivity;, by adopting a sensor array composed of 4 differently doped PPY films it was possible to detect and identify simple organic solvents. The Principal Components Analysis (PCA) was adopted for the pattern recognition process and the first two principal components were sufficient to produce an explained variance of 98,1%.