Sustained NOx reduction at low temperatures, especially in the 150-200 °C range, shares some similarities with the more commonly discussed cold-start challenge, however, poses a number of additional and distinct technical problems. In this project, we set a bold target of achieving and maintaining 90% NOx conversion at the SCR catalyst inlet temperature of 150 °C. This project is intended to push the boundaries of the existing technologies, while staying within the realm of realistic future practical implementation.In order to meet the resulting challenges at the levels of catalyst fundamentals, system components, and system integration, Cummins has partnered with the DOE, Johnson Matthey, and Pacific Northwest National Lab and initiated the Sustained Low-Temperature NOx Reduction program at the beginning of 2015 and completed in 2017. Through this collaboration, we are exploring catalyst formulations and catalyst architectures with enhanced catalytic activity at 150 °C; opportunities to approach the desirable ratio of NO and NO2 in the SCR feed gas; options for robust low-temperature reductant delivery; and the requirements for the overall system integration. This paper will provide information on the approach used and share results of an on-engine performance demonstration on the path towards a commercially viable solution.