The pyrolysis gas and soot production characteristics of propane at different temperatures and residence time were studied experimentally. Based on the combustion mechanism of propane proposed by the University of California, San Diego and Appel mechanism, a new mechanism of propane pyrolysis and soot formation, SD-APP_MECH was established. The reaction paths and dominant controlling reactions of propane pyrolysis and soot production were investigated. According to the experimental results, the new mechanism was optimized to predict the processes of propane pyrolysis and soot formation accurately. The optimized mechanism of propane pyrolysis was named as C3H8_MECH. The results showed that propane begins to pyrolyse at around 970 K, the main components of the syngas are H-2, CH4, C2H2 and C2H4. At the later stage of pyrolysis, C2H2 was generated from C2H4 dehydrogenation at 1150 K. When the temperature is below 1173 K, little soot was produced. However, the soot formation rate increased obviously when the temperature is higher than 1250 K. The soot diameter increased with the temperature increasing, and the amount of soot formation decreased with the residence time reducing. The mole fraction of dominant products in propane pyrolysis and soot formation rate calculated from the C3H8_MECH mechanism agreed well with the experimental values. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.