Abstract Continuous, real-time monitoring of X-ray flux is essential for many synchrotron radiation experiments to ensure accurate normalization and stable operation. Innovative free-standing SiC membrane devices, developed by SenSiC GmbH, show promising potential as beam monitor candidates. In this paper, we present the results of an analysis on the response of SiC membranes to photon energies of 3.5 keV and 8 keV, conducted at the PTB laboratory within the BESSY II synchrotron radiation facility. The high transparency of the tested devices, combined with the ability to extract non-negligible current signals and responsivities, demonstrates their effectiveness for use as beam monitors in synchrotron applications.