Optical limiting behavior of three ferrocenyl substituted calixarenes (FSCs) where ferrocenyl group is attached via ethynyl(a), meta-(b) and para-(c) ethynyl phenyl spacers studied with nanosecond pulses at 532 nm is in the order c >a>b. While, with femtosecond laser pulses at 800 nm strength of nonlinearity is in the order c >b >a. Largest nonlinear refraction (n(2)=9.5 x 10(-16) cm(2)/W) is estimated for the FSC c. Nonlinear absorption in these FSCs is attributed to three-photon absorption. Optical limiting behavior with nanosecond laser pulses is mainly due to thermal nonlinearity and reverse saturable absorption, whereas, with femtosecond laser pulses mainly intrinsic electronic nonlinearity contributes. (C) 2014 Elsevier B.V. All rights reserved.