The effects of H-2 in the feed gasses on the Chichibabin condensation of ammonia with formaldehyde and acetaldehyde for pyridine and 3-picolines synthesis were studied in this work. It was observed that over Pt/ZSM-5 and H-ZSM-5 catalyst hydrogen can moderate the deactivation, depressed the coke formation, slightly lower the initial yield of pyridine bases and increase the selectivity of pyridine over 3-picoline. These effects cannot be simply attributed to the reactant dilution by H-2, while are similar as those of spilt-over hydrogen on a Pt/ZSM-5 catalyst on this reaction. These phenomena are taken as the evidence to support the hypothesis that molecular H-2 is activated by the pure zeolite during the Chichibabin condensation.