Device performance in organic electronics depends on electronic properties of buried interfaces between thin (<100 nm) polymer films and metal. Such properties are determined here for two model systems using Kelvin Probe Force Microscopy. First, three types of micro-patterns of self-assembled monolayer (SAM) on Au (COOH-SAM/Au, COOH-SAM/CH3-SAM, CH3-SAM/COOH-SAM), all covered by polystyrene (PS), are detected with Contact Potential Difference (CPD) to yield maps with different (enhanced or reversed) contrasts. In turn, capacitance gradient signal dC/dz is uniform and PS topography is flat (except for similar to 1 nm variation on COOH-SAM/Au). Second, domains rich in PS and polyaniline (doped with camphorsulfonic acid) (PANI(CSA)), phase-separated in film blends cast on Au, are reflected by topography and dC/dz maps. Surprisingly, CPD signal varies between individual PANI(CSA) domains, indicating their modified interaction with metal substrate. (C) 2013 Elsevier B.V. All rights reserved.