Many studies have been performed to evaluate the environmental risk caused by alternative flame retardants (AFRs) of polybrominated diphenyl ethers due to their ubiquitous occurrence in the environment. However, as an indispensable component of the environmental risk assessment, the information on atmospheric fate of AFRs is limited although some AFRs have been frequently and highly detected in the atmosphere. Here, a combined quantum chemical method and kinetics modeling were used to investigate atmospheric transformation mechanism and kinetics of AFRs initiated by OH in the presence of O2, taking triphenyl phosphate (TPhP) as a case. Results show that the pathway involving initial OH addition to phenyl of TPhP to form TPhP-OH adduct, and subsequent reaction of the TPhP-OH adduct with O2 to finally form phenol phosphate, is the most favorable for the titled reaction. The calculated overall reaction rate constant is 1.6×10(-12)cm(3) molecule(-1)s(-1), translating 7.6days atmospheric lifetime of TPhP. This clarifies that gaseous TPhP has atmospheric persistence. In addition, it was found that ice surface, as a case of ubiquitous water in the atmosphere, has little effect on the kinetics of the rate-determining step in the OH-initiated TPhP reaction.