AbstractThe high temperature pyrolysi of 1,3‐butadiene has been investigated in the shock tube with two time‐resolved diagnostic techniques: laser schlieren measurements of density gradient with 1, 2, 4, and 5% C4H6 in Ar or Kr, 0.26 < P2 < 0.66 atm, over 1550–2200 K, and time‐of‐flight mass spectra for 3% C4H6–Ne, P5 ∼ 0.4 atm, 1400–2000 K. When combined with a recent single‐pulse shock tube product analysis covering 1050–2050 K, these measurements permit a complete modeling of major species in C4H6 pyrolysis. Extrapolated density gradients and product analyses show initiation is dominated by C4H6 → 2C2H3., significant falloff and Arrhenius curvature being seen in the derived rates. A restricted rotor, Gorin model RRKM fit to these rates with reasonable parameters generates The derived barrier, ΔH = 99 ± 4 kcal/mol, translates to ΔH,298 = 63.4 ± 2 kcal/mol for the heat of formation of vinyl radical. A mechanism for the formation of all products detected in the above experiments is given, together with a successful but semiquantitative kinetic model for major products. The measurements require the rate of vinyl radical dissociation, C2H3 + M → C2H2 + H + M, to be extremely low, k < 109 cm3/mol s for 1600 K, so that the dominant chain carrier in C4H6 pyrolysis is vinyl radical.