The thermal reactions of 1-methylindole were studied in the temperature range of 525 deg to 627 deg c in a flow reactor. The major products consisted of 2-methylindole, 3-methylindole, indole, quinoline, hydrogen, and methane. 2-Methylindole is formed from 1- methylindole by an irreversible isomerization reaction. The 2- methylindole isomerizes in a reversible manner to 3-methylindole, the equilibrium favoring the 3-methyl isomer. Indole is formed directly from 1-methylindole. Quinoline is formed from 1- methylindole, 2-methylindole, and 3-methylindole. Work done in cooperation with the University of Wyoming.