The spray ignitions of hydro-processed renewable diesel (HRD), petro-diesel and biodiesel were investigated in a constant volume combustion chamber at low combustion temperatures (LTC) spanning from 600 K to 818 K and various chamber pressures of 10, 15, and 20 bar. These experiments were determined by the reactivity of the fuel and the spray ignition acceleration under engine-related operating conditions. It was found that the first stage and total stage ignition delays were shortened exponentially with increases in the chamber temperature. The HRD fuel was found to obtain the fastest ignition delay compared to diesel and biodiesel. The ignition delays of biodiesel and diesel were similar at the highest chamber pressure and temperature even though biodiesel has a slightly higher cetane number. HRD had the highest reactivity among the fuels, followed by diesel and biodiesel. Additionally, the global equivalence ratio under the lean condition resulted in a lower heat release rate amplitude. Slower fuel reactivity was observed with the maximum amount of carbon double bond in the biodiesel at the lower chamber temperature. The diesel with isomer chain branching had longer reactivity compared to the HRD, which obtains mostly normal alkanes. The NTC zone was clearly observed at a chamber pressure of 15 bar. The region was extended from 725 K to 781 K for the HRD fuels and from 725 K to 818 K for both diesel and biodiesel fuels. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.