The responses of resistive-type sensors based on two poly (monosubstituted)acetylenes, namely poly (N,N-dimethylpropargylamine) (Pd-PDMPA) and poly(propargylalcohol) (PPOH), to relative humidity (r.h.%) and to alcohol vapors were investigated. The polymeric materials Pd-PDMPA and PPOH were doped with HCl or with SnCl2 and I-2, respectively. HCl-doped Pd-PDMPA exhibited detectable response to r.h. percentages as low as 2% and a variation of five orders of magnitude in the r.h. range 0-90%. PPOH doped with SnCl, or 12 varied its conductivity of about four orders of magnitude in the full range of r.h. Both doped polymers showed sensitivity to methanol. A morphological characterization was carried out in order to correlate the differences in the electrical behavior. (C) 2003 Elsevier B.V. All rights reserved.