Research data collected for the submitted article "Graphite protection layers enable halide perovskite based photoanodes for water splitting". Devices were fabricated via solution-based processes and characterised using electrochemistry, photochemistry and optoelectronic methods. The main characterisation techniques used are current-voltage curve measurements, AFM (atomic force microscopy) and SEM (scanning electron microscopy) imaging, XRD (X-ray diffraction), UV-Vis and electrochemical techniques, such as chronoamperometry and voltammetry.