  Though various extensions of the Standard Model with higher gauge group
predict the existence of leptoquarks, none of them has been observed yet at any
of the colliders. In this paper, we study the prospect of several past and
future $e$-$p$ colliders like HERA, LHeC and FCC-he to detect them through
radiation amplitude zero. We find that the leptoquarks showing zeros in the
tree-level single-photon amplitudes at $e$-$p$ collider lie within the
complementary set of those exhibiting zeros at $e$-$\gamma$ collider. We
present a PYTHIA-based analysis for HERA, LHeC and FCC-he (run II) to detect
the leptoquarks with masses 70 GeV, 900 GeV and 1.5 TeV (2.0 TeV) respectively
through radiation amplitude zero.
