To evaluate the heat elevation of FeCo hollow fibers filled in magnetic composite sheet, we synthesized the FeCo hollow fiber by using electroless plating method. The synthesized FeCo hollow fibers (50 wt.%) were mixed with thermoplastic polyurethane (TPU). FeCo hollow fiber in composite sheet exhibited the representative alpha-FeCo peak by XRD. The magnetization and coercivity of FeCo hollow fibers were 176.5 Am-2/kg and 6.2 kA/m, respectively. In order to measure the heat elevation, the alternating magnetic field (AMF) was applied to magnetic composites sheets from 7.1 kA/m to 11.1 kA/m at 190 kHz and the frequency was applied from 190 kHz to 355 kHz at 8.3 kA/m, respectively. The elevated temperatures and the specific loss power (SLP) values exhibited about 76 degrees C from the initial temperature of 26 degrees C and about 25.3 W/g for the AMF of 8.3 kA/m and frequency of 355 kHz. (C) 2016 Elsevier B. V. All rights reserved.