The vapor phase catalytic decomposition of methyl nitrite over supported palladium catalysts has been investigated. The catalytic activities were ranked in the following order: Pd/gamma-Al2O3 > Pd/A.C > Pd/alpha-Al2O3 >Pd-Ti/alpha-Al2O3. The acidic supports, such as HY zeolite, gamma-Al2O3 and SiO2 also exhibited moderate activity for methyl nitrite decomposition reactions. Several unusual features in the present decomposition reactions of methyl nitrite are discussed. A possible successive dehydrogenation mechanism was proposed to explain the facts observed in this study.