Nanosized strontium ferrite powder was deposited with Ni-P by electroless plating under the agitation of ultrasonic wave at. room temperature. The morphology, crystal structure, complex permittivity and complex permeability of the composite powder were investigated with field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive analysts of X-rays (EDS) and vector network analyzer. The results show that the imaginary part of complex permeability of the strontium ferrite powder is increased greatly by the deposited Ni-P layer. The application of the nanocomposite powder as microwave absorber is promising. (c) 2006 Elsevier B.V. All rights reserved.