In metazoans, the acidification of the phagosomal lumen is essential for the efficient degradation of cargoes. Here, we present a protocol for measuring the rate of acidification inside phagosomal lumen containing apoptotic cells in living C.&#
xa0;elegans embryos. We describe steps for generating a worm population, selecting embryos, and mounting embryos on agar pads. We then detail live imaging of embryos and data analysis. This protocol is applicable to any organism in which real-time fluorescence imaging can be performed. For complete details on the use and execution of this protocol, please refer to Pena-Ramos et&#
xa0;al. (2022).<sup>1</sup>.