An examination of the interface between Cr and cured polyimide (PI) was carried out using x-ray photoelectron spectroscopy and transmission electron microscopy. The results indicate that, after curing, the interface remains sharp and planar, at least on a submicron scale, with no discernible material mixing or mechanical interlocking. During Cr metallization of cured polyimide (PI) at room temperature, the first few monolayers of Cr appear to react with the pendent oxygen in the PI substrate. This layer of oxidized Cr atoms forms chemical bonds with PI on the one side, and metallic bonds with the subsequent Cr deposit on the other. It is estimated that the interfacial reaction may give rise to an eightfold increase in intrinsic adhesion strength of the Cr/PI system as compared to Cu/PI couples for which no interfacial reaction have been observed. © 1984, The Electrochemical Society, Inc. All rights reserved.