An investigation of the nonlinear absorption of a wide range of structurally diverse porphyrin monomers, bisporphyrins and trisporphyrins, using open Z-scan technique with 6 ns pulsed laser operating at 532 nm was carried out. Using the theory of reverse saturable absorption, the intensity dependent nonlinear absorption coefficient beta(eff) was deduced from the experiments. Monomers which Soret band maximum was situated closer to the experimental wavelength had higher beta(eff). The beta(eff) of dimers and trimers were in the same range as for monomers. The highest beta(eff) = 5.3 x 10(-8) cm W-1 was found for a zinc complex of 5,15-A(2)B(2) type porphyrins with 3-methoxyphenyl and trimethylsilyl-ethynyl groups in the meso positions. (C) 2009 Elsevier B. V. All rights reserved.