A comprehensive chemical mechanism has been developed to describe combustion of the refrigerant HFO-1234yf (2,3,3,3-tetrafluroropropene, YF), revealing the dominant pathways for its stoichiometric combustion with O-2. This novel mechanism is a quantum-chemistry-based extension to a previous mechanism developed at NIST for small fluorinated hydrocarbons. The new reactions were proposed by analyzing the YF molecule for potential unimolecular and bimolecular destruction routes, including chemical-activation channels. Kinetic parameters and thermochemistry were calculated using computational quantum chemistry or were developed by analogy to similar reactions or species. The new mechanism was compared favorably to experimental adiabatic-flame-speed data for stoichiometric YFI(35% O-2/65% N-2) flames at different initial temperatures. Analyses of these predictions revealed the key YFdestruction step at this H-starved condition to be F addition, producing CH2CF2+CF3 via chemically activated (center dot CH2CF2CF3)*. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.