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We have successfully prepared monofilamentary MgB2 wires and tapes with different sheathed metals such as Cu, Ta/Cu and Fe by the powder-in-tube method. The phase composition, superconducting properties and microstructure features are investigated by x-ray diffractometer, the standard four-probe technique, SQUID magnetometer, SEM and TEM. The results indicate that Jc in MgB2/Ta/Cu wires is higher than 105 A cm−2 at 5 K in 0.1 T and 104 A cm−2 at 20 K in 1 T. By Ti-doping, Jc can be significantly improved. MgB2/Fe wires show very high transport critical current densities of 1.43 × 105 A cm−2 (4.2 K, 4 T), 3.72 × 104 A cm−2 (15 K, 4 T) and 2.34 × 104 A cm−2 (25 K, 3 T). Also the results indicated that small grain size should respond to the large Jc in Ti-doped MgB2 tape and MgB2/Fe wire.