Using observations made by the solar wind ion composition spectrometer on Ulysses during its trip in the ecliptic plane to Jupiter, we examined the temperature ratios T(4He2+)/T(H+) and T(O6+)/T(H+) across 15 shocks, including forward and reverse shock pairs as well as isolated shocks. The mean value over the whole set of downstream data studied was 7¿3 for the T(4He2+)/T(H+). Appreciable differentiated heating downstream of a shock occurred for an upstream ratio T(4He2+)/T(H+)<4.5. Downstream in the shock regions, characterized by a quasisteady plasma flux, values of T(4He2+)/T(H+) and T(O6+)/T(H+) are observed in the range 4.6 to 10.8 and 19 to 48, respectively. Downstream of the shock, extra-heated ions heavier than H+ added a mean 13¿6% to the ions' plasma pressure. (This is in addition to the pressure calculated using the common assumption of a temperature scaling with the ion masses in heliospheric collisionless plasma.) The extra heating of 4He2+ relative to H+ was larger for a smaller plasma &bgr;, agreeing with the prediction of the magnetohydrodynamic calculations by Zhao et al. [1991>, although they appeared to underestimate the amount of added heating by a factor of 1.25 to 2.¿ 1997 American Geophysical Union