The beam collision cell technique has been employed to determine the absolute cross sections for the formation of molecular hydrogen ions from reactions of He+(1s) with H2(X1Σg+, υ = 0). The subthermal rate coefficient for the formation of H2+(X2Σg+, υ′)+He(X1S) is presently obtained as 1.48×10−13 cm3 s−1. This result is estimated to be correct to within a factor of 2. The near thermal cross section data are well represented by the expression σ(EFC) = AER−12, where A = 4.91 × 10−33 m3kg12 s−1 and ER is the relative energy. The present evidence for H2+ from thermal He++H2 collisions supports our previous theoretical and experimental results. The mechanism is associative radiation:He++H2⇌He+H2; He+H2→[HeH2+]+hv(153nm); [HeH2+]→He+H2+. The measured cross section for H2+ drops precipitously as the relative collision energy is raised from new zero to about 2 eV. Then the total H2+ cross section rises again as the channels yielding helium He(1s2) and Rydberg molecular hydrogen ion states, H2+*(j2A), open up. The cross section remains large above 4 eV all the way up to 57 eV, supported by access to a second series of Rydberg channels, namely He*(1snl)+H2+(X2Σg+, υ′ above 13 eV. The reaction of H2+ with H2 to yield H3+(X1A1)+H(1s) was also examined—the rate at quasithermal collision energies is presently obtained as 1.7×10−9 cm3 s−1, in excellent agreement with previous work. Further theoretical analysis shows that the H2+*(j2A) from extrathermal He++H2 collisions are the Rydberg states H2+(2sσg, 2pσg, 2pπu, etc.). The mechanism for their formation is similar to that previously discussed for H+ and HeH+. That is, a two electron transition 1σ2σ2→ 1σ24σ, where 1σ = 1sHe, 2σ = 1sσgH2 and 4σ = nl2AH2+ n ⩾ 2, occurs for collisions with collision energy sufficient to take the HeH2+ system up the potential surface for the 22Av′ valence state of the reactants to the relevant avoided intersection with the triatomic Rydberg states arising from the asymptotes He(1s2)+H2+*(j2A), n ⩾ 2. However, in this case the avoided intersection is encountered at extended value of the coor̄dinate RHH. Consequently, only that fraction of the collitions involving HeH2 orientations near the colinear Coov coordinate will be effective. For this reason, the extrathermal cross sections for H2+* are apparently low compared to those previously reported for H+ and HeH+. Similar considerations apply to the somewhat higher lying HeH2+ channels leading to the He*(1snl) + H2+(X2Σg+) channels, which are accessed via one-electron transitions at the relevant avoided intersections of HeH2+ 2A′ states.