This folder contains the experimental data set for the paper "In-situ water purification with a zero-gap flow cell electrolyzer for seawater electrolysis". Please check the "READ ME" file in the folder for more information about the experimental data set. The folder should contain: READ ME (both in text file and .md file): which contains the explanation of the tests and terminology required to understand the experimental data. Both files can be opened with Notepad. Cell configuration (sub-folder): which contains the 3D drawing of the flow cells. Continuous pH measurement (sub-folder): which contains the pH measurement data during the stability test. DCMD modeling (sub-folder): which contains the Python code to simulate the water transport rate across the PTFE membrane in different conditions. Electrochemical measurement (sub-folder): which contains the electrochemical data during the stability test. Surface analysis (sub-folder): which contains the SEM/EDX/XPS analysis data used in the paper and the SI. Water transport rate measurement (sub-folder): which contains the water transport rate data for both PTFE-based and FO-based water purification systems, as well as the selectivity test for FO-based water purification. IC measurement (Excel document): which contains the IC measurement data for the stability test. Solution weight change measurement (Excel document): which contains the solution weight measurement for the stability test.