Carbon nanofibers with uniform diameter distribution are of great importance to be applied in composite materials production. Characteristics of the final carbon product obtained via catalytic chemical vapour deposition are known to be determined by the catalyst characteristics and the process conditions. In this work, ultrasonic spray pyrolysis was used for the preparation of uniform-sized NiO-CuO-MgO fine powders. Spherical particles of 170-340 nm in diameter were obtained in a temperature range of 400-600 degrees C. Synthesized powders exhibited high catalytic activity in CCVD of ethylene with the formation of CNF with relatively narrow diameter distribution (60 +/- 20 nm). (C) 2017 Elsevier B.V. All rights reserved.