In this paper gluon admixtures in neutral pseudoscalar mesons are considered to test the quark-line rule for the reactions πp→η∆, ηn, p(Formula Presented)→ππη, etc. It is found that the experimental data on these reactions support the possibility of a small gluonium admixture in the η and η' states. Our results have also been used to predict some electromagnetic decay rates of the pseudoscalar glueball states l(1440) along with those of η and η'. © 1986 The Institute of Physics.