  We study instanton contributions to hadronic decays of the scalar glueball,
the pseudoscalar charmonium state $\eta_c$, and the scalar charmonium state
$\chi_c$. Hadronic decays of the $\eta_c$ are of particular interest. The three
main decay channels are $K\bar{K}\pi$, $\eta\pi\pi$ and $\eta'\pi\pi$, each
with an unusually large branching ratio $\sim 5%$. On the quark level, all
three decays correspond to an instanton type vertex
$(\bar{c}c)(\bar{s}s)(\bar{d}d)(\bar{u}u)$. We show that the total decay rate
into three pseudoscalar mesons can be reproduced using an instanton size
distribution consistent with phenomenology and lattice results. Instantons
correctly reproduce the ratio $B(\pi\pi\eta)/B(\pi\pi\eta')$ but over-predict
the ratio $B(K\bar{K}\pi)/B(\pi\pi\eta(\eta'))$. We consider the role of scalar
resonances and suggest that the decay mechanism can be studied by measuring the
angular distribution of decay products.
