Porous FeNi powders with particle size of 1 Ism were successfully prepared by two steps in this paper. First, Fe0.5Ni0.5C2O4 center dot 2H(2)O particles with uniform size distribution and morphology were obtained by an oxalate precipitation process. Second, the porous FeNi powders were prepared by thermal decomposition of the oxalate precursor at 450 degrees C for 30 min in a N-2/H-2 mixed atmosphere. The electromagnetic (EM) parameters of FeNi (30 wt%)/paraffln composite were measured in 2-18G Hz, and the reflection loss (RL) values were calculated based on the transmission line theory. The results show that the bandwidth of RL <-10 dB reaches 2.57G Hz when the composite thickness is 2.0 mm, and the minimum RI. reaches -52.58 dB at 6.82G Hz with a composite thickness of 3 mm. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.