Direct ionization processes of hydrogen-like atoms by proton impact are investigated by Born theory. The triple diferential cross sections (TDCSs) and the quantities of physical interest in the process are calculated for ionization of H, He+, Li2+, and Be3+ ground-state atoms, using the frst- and second-Born approximations. The closure relation is employed to come over the consideration of the intermediate states. The calculations are carried for fxed scattering angles and ejected electron energies at the impact energies 75, 200, and 500 keV. The infuence of each of the incidence energy and the atomic number of the target atom on the TDCSs is studied. The contribution of the second-Born term to the cross section is illustrated