Raw, reconstructed and segmented data and first processing step of X-ray tomographic microscopy (XTM) on wicking in yarns. The data collection contains the recorded (raw) projection images for sequential tomographic scans stored as hdf5 files in the folder "raw_data". Reconstructions are provided as tiff stacks per time step in "reconstructed_data". Finally, post-processed data as used for the adjunct article are included in "processed_data" as netcdf4 files and segmented fibers as tif-stacks. Image processing was performed with the python codes available on github.com/Pescatore23/TOMCAT_processing. The processed data and processing codes are provided as is to serve as example. Data were collected and reconstructed at the TOMCAT beamline X02DA of the Swiss Light Source.