The multi walled carbon nanotubes grown by the CVD technique were suspended in methanol and their linear and non-linear transmission properties have been studied. It is observed that the linear transmission spectrum, measured in the range 450-1100 nm, depicts features similar to those of single walled nanotubes. The observed features may be well characterized as the van-Hove singularities of the one-dimensional electronic density of states. Further, excellent non-linear optical properties have been observed in these suspensions. Experiments are conducted to study the optical limiting behavior in the visible (532 nm) as well as in the near infra-red (1064 nm) region by using a dual beam pulsed pump-CW probe, technique. The grown multi walled carbon nanotubes show a strong limiting behavior at both of these wavelengths. The recovery time as observed from the probe beam transmission is measured at different values of the incident pulse energy. The results are discussed in the light of the existing results. (c) 2005 Springer Science + Business Media, Inc.