NVN-ISO/TS 19006 describes how to test and evaluate results obtained from in vitro ROS generation in RAW 264.7 macrophage cells exposed to nano-objects, nanoparticles, their aggregates and agglomerates using the CM-H2DCFDA assay. The protocol in this document is limited to use of a 24 well plate so if other plates were to be used, volumes would need to be adjusted and the protocol steps validated to ensure confidence in the test results.