The interface between evaporated Ti and PMDA/ODA polyimide is examined using several techniques. The formation of small TiO2particles at this interface (15 to 40 &mgr;m diameter, ca.30 nm thickness, covering about 6% of the interfacial area) is demonstrated. The failure is of cohesive type in the polymer layer. When the residual pressure during Ti evaporation is increased, the number of TiO2particles increases, adhesion of the Ti layer is lowered and the locus of failure is closer to the metal layer. When an oxygen plasma treatment is performed onto PMDA/ODA prior to Ti evaporation, the failure mode remains cohesive in the polymer layer. However the failure occurs at the modified/unmodified polymer limit.Abinitio(SCF) calculations were finally performed on models of the PMDA‐ODA polyimide in interaction with one Ti atom, in order to determine the most favorable interaction sites of this metal with the polymer. The most favorable interaction corresponds to the formation of a complex between Ti and the aromatic ring of the PMDA unit. Other possible sites of interaction are, in decreasing order of stability: the heterocycle of PMDA, the ≳C=O groups of PMDA and the ODA aromatic ring. Calculations of the core MO energies for the various model situations, show that it is not possible to account for the low energy C1s peak observed at ca.282 eV. Introduction in the model of a Ti atom bonded to one of the aromatic carbons permits to account for this peak. Thus, the existence of Ti‐C bonds in the polyimide‐Ti system is clearly confirmed. ©1996 American Institute of Physics.