In the present work, the porous hollow carbon spheres loaded with NiFe2O4 nanoparticles have been successfully prepared via ultrasonic spray pyrolysis technique at 700 degrees C and the associated formation mechanism has been studied. The as-prepared NiFe2O4/carbon microspheres with the diameter of about 3-5 mu m and the specific surface area of 236.6889 m(2) g(-1) exhibit good monodispersity and an abundance of mesopores of about 40 nm size. Notably, the 20 nm NiFe2O4 nanoparticles are encapsulated by carbon microspheres and disperse homogeneously inside the carbon matrix. We could tune the relative content of ferrite and carbon sphere via adjusting the composition of the solution used for synthesis and the carbonization temperature. Consequently, some interesting properties can be obtained by combining the magnetic NiFe2O4 nano powder and the electrically conductive porous carbon, which renders the resulting composite suitable for promising applications in electromagnetic wave absorption, treatment of polluted water, catalyst design, energy storage, batteries and so on. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.