  Using collinear factorization, we have calculated twist-six corrections to
$\eta\gamma$ and $\eta^{\prime}\gamma$ transition form factors in QCD. Only a
sub-set of light-cone operators of twist-six which can be factorized as a
product of two gauge invariant operators has been considered. Resulting power
corrections start as $1/Q^{4}$ but coefficients are smaller compared to their
counterparts for twist-four operators. Matrix element of pseudoscalar quark
densities for $u$- and $d$-quarks between vacuum and meson state, $h_{q}$, has
considerable influence on the result. Results obtained by superimposing our
results on those obtained in literature for leading and sub-leading power
corrections for lower twists have been plotted and compared with data.
