The reactions of CO+, CO2+, SO2+, NO2+, CS2+, CN+, C2N2+, and C2H3+ with H atoms and H-2 molecules have been studied in a selected ion dow tube operated at (300+/-5) K. The H atom reactions proceed variously by the processes of atom exchange and charge transfer (when allowed), none proceed at the Langevin rate, and the rates of several of them appear to be influenced by the spin states of the product species. Most of the H-2 reactions proceed by H atom abstraction and at a large fraction of the Langevin rate.