The discovery of over 250 painted inscriptions in Anatolian hieroglyphic script at Ḫattuša has revolutionised our knowledge of the literacy of the Hittite civilisation. In this article, after a general illustration of this extraordinary discovery, we analyse a particular logogram, that for ‘Donkey’, present in one of the inscriptions, whose formal analysis allows us to date this painted epigraphic corpus to a particularly ancient period of Hittite history.