  We give explicit formulae for the anomalous chromomagnetic dipole moment of
the top quark in the framework of the standard model, the two higgs doublet
model and the minimal supersymmetric standard model. Finally, we compare the
results for this coupling with the bound -0.03 <= Delta kappa <= 0.01 coming
from analysis of b --> s gamma process whith an on-shell gluon.
