A π-conjugated soluble oligomer of propargyl acetate(OPAT) was synthesized with a novel palladium acetylide catalyst [Pd(C≡CCH2OOCCH3)2(PPh3)2](PPA). Its molecular weight (Mw) is 4500. Some features and kinetic behavior of PAT polymerization with PPA catalyst are described and discussed. The overall polymerization activation energy was found to be 110.2kJ/mol and the rate equation can be expressed as Rp=kp[PAT]1.5[PPA]1.5

where kp=6.58×10-4L2mol-2s-1.The oligomer (OPAT) doped with a solution of FeCl3 in THF exhibits humi-sensitivity. The impedance of doped OPAT (DOPAT) varis about two orders of magnitude (106～104Ω)

when relative humidity (RH%) changes from 11% to 96%.