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An experimental study, supported by computation, was conducted on the coupling of NTC-chemistry and transport in the low-temperature ignition and the associated steady burning in nonpremixed DME/air counterflow. In particular, the presence of low-temperature chemical reactivity was detected nonintrusively by using a photomultiplier tube combined with a filter to capture the chemiluminescence of HCHO, which is a characteristic intermediate species formed in low-temperature chemistry. Furthermore, the ignition temperature was determined through high-sensitivity infrared imaging with proper discrimination of the background signal. Experimental results show that the transport-coupled low-temperature, NTC chemical reactivity is enhanced with smaller strain rate, higher air boundary temperature, and is insensitive to the fuel concentration. These findings agree well with those obtained from computation using …