Ag sheathed Bi-2223 tapes have the performances of I c values over 100A and length of 1000m which are enough for prototype configuration. However, their AC loss is still too high for the practical applications. To reduce the AC coupling loss, the introduction of high resistive barrier between the filaments and the twisting of the filaments are effective. In this study, we try to introduce CuO barrier between the filaments through the in situ metal oxidation method. A silver tube packing Bi-2223 precursor powder was inserted into a copper metal tube. The Ag–Cu clad tubes were stacked into Ag pipe to form a 7-filamentary wire, and the stacked wire was drawn and rolled into tape shape. The Cu inter-filamentary layers were uniformly arranged between filaments of the tape. To oxidize this Cu to form CuO, the pre-oxidation of Cu before heating up to sintering temperature is found to be required to avoid the eutectic melting of the Ag–Cu system. The CuO layer was successfully formed after sintering using the pre-oxidation process, and the J c value of the tape with the CuO layer reached 1.5×10 4 A/cm 2 . The continuity of CuO layer, however, became worse after final sintering, and this must be improved, for example, by increasing the thickness of Cu layer before sintering.