Large-scale synthesis of segmented carbon nanofibers (SCNFs) by catalytic decomposition of acetylene on fan shaped foam Ni in an improved conventional reactor is reported. The procedure can be scaled up for semi-continuous production of the deposits. The effects of the reaction conditions on the growth of the segmented carbon nanofibers are discussed. Samples of the deposits in as-prepared state were examined by means of XRD, SEM, TEM and HRTEM. The results indicate that a semi-continuous synthesis of 10 g of deposits with about 90% segmented nanofibers was obtained at flow rate of acetylene 15 ml/min and hydrogen 150 ml/min at temperature 600degreesC for 30 min. The HRTEM image revealed that the fibers are stacked with well ordered graphitic platelets intermittently spaced by less ordered graphitic platelets perpendicular to the axis of the fiber. The growth mechanism of the segmented carbon nanofibers is also discussed. (C) 2005 Springer Science + Business Media, Inc.