Initiation of therapeutic hypothermia (TH) within 6 h of life is a major concern for treating neonatal hypoxic ischemic encephalopathy (HIE). We aimed to determine clinical and healthcare organizational factors associated with delayed TH in a French population-based cohort of neonates with moderate/severe HIE. Time to reach a rectal temperature of 34 degrees C defines optimal and delayed (within and over 6 h, respectively) TH. Clinical and healthcare organizational factors associated with delayed TH were analysed among neonates born in cooling centres (CCs) and non-cooling centres (non-CCs). Among 629 neonates eligible for TH, 574 received treatment (91.3%). TH was delayed in 29.8% neonates and in 20.3% and 36.2% of those born in CCs and non-CCs, respectively. Neonates with moderate HIE were more exposed to delayed TH in both CCs and non-CCs. After adjustment for HIE severity, maternal and neonatal characteristics and circumstances of birth were not associated with increased risk of delayed TH. However, this risk was 2 to 5 times higher in maternities with < 1999 annual births, when the delay between birth and call for transfer (adjusted odds ratio [aOR] 2.47, 95% confidence interval [CI] [1.03 to 5.96]) or between call for transfer and admission (aOR 6.06, 95%CI [2.60 to 14.12]) was > 3 h and when an undesirable event occurred during transfer (aOR 2.66, 95%CI [1.11 to 6.37].