The reaction of N,N-diethylpropargylamine with increasing amounts of the complex [Ni(NCS)(2)(PPh3)(2)] leads to pi-conjugated organometallic polymers containing Ni(II). XPS measurements show the presence of paramagnetic metal centers, which coordinate two NCS ligands, one phosphine and NEt2 pendant group of the polyenic chain. The number of Ni-bonded atoms increases by increasing the complex/monomer molar ratio. The organometallic polymers are promising materials for humidity sensors, giving reproducible results for various subsequent cycles of relative humidity variations in the range 60-90%.