Iron oxide (Fe3O4) nanowires encapsulated in carbon microtubes (defined as "CIOs") with a diameter range of 150-1500 nm, and lengths up to 6 um were obtained by pyrolyzing an ethanol/ferrocene mixture in an autoclave at 600 degreesC. The inner Fe3O4 nanowires (defined as "IOs") are single crystalline with a diameter range of 55-750 nm. Magnetic hysteresis loop measurements show that the CIOs display ferromagnetic properties at room temperature. In addition, carbon microtubes (CMTs) were obtained after the inside IOs were dissolved by aqueous HCl acid.