The heterophase interface between a metal and a ceramic is of great practical importance because of the ubiquitousness of this interface in composite materials, thin film technology and electronic packaging systems. The nature of the chemical bond at a metal/ceramic interface is very important in determining how well these two disparate materials adhere to one another, and ultimately the performance of this heterophase interface in service. On the basic side the question of the nature and strength of the chemical bond at a metal/ceramic interface has been addressed recently from a first principles point-of-view [1,2]. In addition, much experimental effort has been expended recently employing high resolution electron microscopy (HREM) to determine the terminating plane on the oxide side of metal/metal oxide heterophase interfaces by comparing observed HREM images with computer simulated images [3-5]. In this paper we present a combined transmission electron microscopy, HREM and atom-probe field-ion microscopy (APFIM) study of a Cu/MgO heterophase interface produced by internal oxidation of a Cu(Mg) alloy. This heterophase interface is an interesting one as it consists of joining a noble free-electron metal (Cu) to a strongly heteropolar metal oxide (MgO). We demonstrate, for the first time, that by combining these three microscopies it is possible to determine the chemical identity of the terminating plane on the oxide side of a Cu/MgO { 111 }-type interface directly without any deconvolution of the experimental data. In particular, we demonstrate that the bonding across a Cu/MgO {l l l} type interface, in a common direction, has the sequence CulOIMgl... and not CulMglOI... via APFIM measurements of this highly localized chemistry.