Abstract: The thermal and catalytic cracking reactions of 2,5-dimethylhexane were carried out at 550—650 ℃ at low conversion (x < 15%) in a pulse micro-reactor over quartz and ZRP zeolite，respectively. Formation mechanism of methane was analyzed. The results show that methane, propylene and i-butylene are the primary products in thermal cracking. There are three reaction pathways that contribute to the methane formation during chain propagation through the hydrogen extraction from C—H bond by methyl radical. The C—H bond attached to the tertiary carbon shows higher reactivity and accounts for more than 90% of methane selectivity during thermal cracking. The conversion and product distribution are clearly influenced by shape-selective catalysis and the methane is produced by protolytic cracking reaction during the catalytic cracking of 2,5-dimethylhexane over ZRP zeolite. The comparison of the contribution to methane between thermal and protolytic cracking pathways reveals that methane is mainly formed by thermal cracking, which gradually enhances along with the increase of reaction temperature.