Measurements are reported of the total cross section for deactivation of neon3P2and3P0(2p53s) metastables by inelastic collisions with H2, D2, CH4, and NH3. Observations were conducted by applying the methods of resonance radiation absorption and microwave diagnostics to the afterglow plasma following a weak pulsed discharge in a neon‐hydrogenic impurity mixture. The cross section for3P2deactivation by H2was found to increase from 0.7×10−15cm2at 300°K to 2.5×10−15cm2at 650°K. The cross section for ionization of H2by Ne*3P2collision was found to represent only a fraction of the above. The reaction which dissociates H2and partly converts the metastable energy into H&agr;(6563 Å) light has been observed in H2, D2, CH4, and NH3and may represent a significant contribution to the total deactivation in each case. No H&agr; light was produced as a result of the destruction of a helium3S1metastable by collision with H2.