A novel hyperbranched polyyne (hb-DPP) with triphenylamine as the core, 2,5-dioctylpyrrolo [3,4-c]pyrrole-1,4 (2H,5H)-dione (DPP) as the connecting unit has been designed and synthesized by Glaser-Hay oxidative coupling reaction, which was characterized by IR, NMR, UV-vis, FL, and GPC. The polymer exhibits high molecular weight (M, up to similar to 6.55 x 10(4) Da) and is readily soluble in common organic solvents such as toluene, chloroform, tetrahydrofuran, N,N-dimethyl formamide and so on. The one- and two-photon absorption (TPA) properties have been investigated. The TPA cross section of the polymer was measured by open-aperture Z-scan experiment using 140 ferntosecond (fs) pulse, and the TPA cross section for hb-DPP was determined to be 579 GM per repeating unit at wavelength of 800 nm. In tetrahydrofuran, hb-DPP exhibits intense frequency up-converted fluorescence with the peak located at 584 nm under the excitation of 800 nm fs pulses. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4400-4408, 2009