The quantitative detection of reaction products at low temperature is crucial for the understanding of low-temperature chemistry, in part due to the increased importance of quantum effects as the temperature is lowered. Product information and branching ratios at very low temperatures are also vital input for astrochemical models. Early mass spectrometry experiments have allowed the detection of reaction products in a pulsed CRESU flow down to 90K, while spectroscopic techniques have enabled the measurement of H atom branching ratios down to 50K. Coupling CRESU flows to multiplex mass spectrometry at synchrotron facilities has already provided branching ratios between isomers formed by the same reactions below 100K. The newly designed CRESUSOL apparatus using photoion-photoelectron coincidence detection scheme has the ability of detecting reaction products down to 10K. Chirped-pulsed microwave spectroscopy has also appeared as a sensitive and universal technique for the detection of isomer-resolved products. The cold rotational distributions in the CRESU flow provide ideal conditions for detection of products and also give the advantage of being able to distinguish isomers of products through their rotational spectra. These universal, isomer-resolved detection techniques and others, like frequency comb spectroscopy, have only just started to be implemented to CRESU apparatuses and promise to provide a wealth of information about gas phase chemical and physical processes occurring close to the absolute zero. © 2022 by World Scientific Publishing Europe Ltd.