  We studied the scalar electrodynamics ($SQED_{4}$) and the spinor
electrodynamics ($QED_{4}$) in the null-plane formalism. We followed the
Dirac's technique for constrained systems to perform a detailed analysis of the
constraint structure in both theories. We imposed the appropriated boundary
conditions on the fields to fix the hidden subset first class constraints which
generate improper gauge transformations and obtain an unique inverse of the
second class constraint matrix. Finally, choosing the null-plane gauge
condition, we determined the generalized Dirac brackets of the independent
dynamical variables which via the correspondence principle give the
(anti)-commutators for posterior quantization.
