The first observations of a high energy ion shock spike extending in energy to > 25 MeV for protons, > 4.3 MeV/nuc for alpha particles, and > 1.6 MeV/nuc for medium nuclei with Z ≥ 6 are reported. The measurements were obtained in the course of a solar particle event on September 15, 1974 by The Johns Hopkins University/Applied Physics Laboratory (JHU/APL) experiments on the IMP‐7 and IMP‐8 spacecraft. It is shown that the observations can be reasonably accounted for by intensive acceleration of charged particles at an "almost" perpendicular interplanetary shock wave. The data are inconsistent with a one‐step d.c.‐type acceleration process.