The recently suggested possibility of catalytic destruction of H by C2H2 in the Jovian upper atmosphere has been examined. For this purpose we discuss a relatively more detailed chemistry, including the possible role of the reaction C2H2+C2H3→C4H5*→C4H4+H, and wish to suggest that the catalytic destruction of atomic hydrogen is quite questionable at least under the present paucity of the required reaction rate data. Attention is also drawn to the importance of the temperature dependence of the rate coefficients in discussing Jovian aeronomy.