A combination of the complex (1-Me-indenyl)(PPh3)Ni-CdropC-Ph and methylaluminoxane (MAO) catalyzes the polymerization of 1-ethynylpyrene to fairly soluble cis-poly(1-ethynylpyrene). The polymers have been characterized by IR, solid state C-13 and H-1 NMR, and UV-Vis (lambda(max) at 346 nm) spectroscopy, and studied by thermogravimetric analysis (T-10 similar to 285-392degreesC), differential scanning calorimetry, and size exclusion chromatography (M-w similar to 10(3)-10(4) Da; M-w/M-n similar to 2). The thermal and optical properties of these cis-polymers have been compared to their trans-analogues prepared using different catalysts. The degree of conjugation in the cis-polymers was found to be lower than their trans-polymers, presumably due to the twisting and coiling of the main chain. (C) 2003 Elsevier Science B.V. All rights reserved.