Abstract
A study of the discrete spectra of the Schrödinger and Dirac equations for the delta-shell potential 
in momentum space is presented in this paper. As a general rule, the spectra for exactly solvable potentials are more easily obtained in position space than in momentum space. The delta-shell potential is unique, since its treatment is simpler in momentum space than in position space. This simplicity derives from two facts; firstly, the kernels of the integral equations in momentum space turn into the product of two independent functions, and secondly, no explicit analysis of the boundary condition for the wavefunction is necessary at 
.