[en] Absolute and relative cross sections were obtained for the Penning ionization (PI) reaction Ne* + Ar → Ne + Ar⁺ + e and the associative ionization (AI) reaction Ne* + Ar → NeAr⁺ + e by a merging-beams technique over a range of interaction energies W from 0.01 to 600 eV. The Ne* represents a composite of Ne(3s ³P₂) and Ne(3s ³P₀). The PI cross section Q/sub Ar⁺/ rises with decreasing W except for a small dip near 0.05 eV and exhibits a rather weak dependence on W. For a change of almost five orders of magnitude in W, Q/sub Ar⁺/ only changes by about a factor of 7. The AI cross section Q/sub NeAr⁺/ monotonically increases with decreasing W and shows a large dependence on W. The Q/sub NeAr⁺/ at W = 0.01 eV is about 70 times larger than that at 0.5 eV. The total cross section Q/subT/ = Q/sub Ar⁺/ + Q/sub NeAr⁺/ is compared with theoretical and other experimental values. At low W our absolute Q/subT/ are considerably larger than those of Tang, Marcus, and Muschlitz although the relative Q/subT/ for both experiments are in fair agreement