Two-dimensional (2D) epitaxial materials including hexagonal boron nitride (hBN) are frequently employed as templates for self-assembled molecular films and nanostructures [1]. A quantitative structural characterization of the respective interfaces and adsorbate geometries however is largely missing. After reviewing some examples of molecular self-assembly on hBN, I will report on the geometric and electronic structure of a prototypical organic/insulator/metal interface, namely metalloporphines (Co-P, Zn-P) on hBN/Cu(111), investigated by combining X-ray photoelectron spectroscopy, X-ray...