We investigate the prospects for discovering a top quark decaying into
one light Higgs boson ($h^0$) along with a charm quark
in top quark pair production
at the CERN Large Hadron Collider (LHC) and future hadron colliers.
A general two Higgs doublet model is adopted to study the signature
of flavor changing neutral Higgs (FCNH) interactions with $t \to c h^0$,
followed by $h^0 \to WW^*$ and $\tau^+\tau^-$.
We study the discovery potential for the FCNH signal and physics background
from dominant processes with realistic acceptance cuts and
Promising results are found for the LHC running
at 13 or 14 TeV collision energies as well as
future pp colliders at 27 or 100 TeV.