High-resolution electron energy loss spectroscopy and low-energy electron diffraction have been used for studying the early steps of water interaction at 100 K with clean and K-doped quasi-freestanding graphene epitaxially grown on Pt(1 1 1). Loss measurements indicate the formation of a disordered ice structure and do not support the proposal of a new ice polymorph in this system in published literature. When dosed at 100 K onto a potassium-precovered graphene sheet, water molecules dissociate giving rise to C–H vibrational bands.